I want/need to replace a few relay-logic controls with PLCs. Typically, a
machine is using 6 to 8, 3 or 4 pole DT relays, 6 to 8 limit switches and 3
to 4 operator switches, and 4 to 6 hydraulic/pneumatic valves. Should be
ideal for PLCs. I need to learn ladder programming. On the web, there are
plenty of tutorials but everything I've seen or tried is lacking in
translating the real-life process into a program. Any direction I should
look? A lot of my stuff is old and doesn't have schematics yet alone a flow
chart. The guy I had that was very good at this retired and moved to SC.

PLCs only make sense when you have sequential events that are dependent on previous events, like motion fault detection. From what
I have gleaned from previous postings is that your equipment is mechanically timed. In my humble opinion I would concentrate on
using electronic trigger technology, solid state relays and motion validation logic (feedback). The value of doing this is first
reliability and secondly immediate system fault identification. You should be able to use a common family of components for all
your solutions.
Steve

"Buerste" wrote in message ...
I want/need to replace a few relay-logic controls with PLCs. Typically, a machine is using 6 to 8, 3 or 4 pole DT relays, 6 to 8
limit switches and 3 to 4 operator switches, and 4 to 6 hydraulic/pneumatic valves. Should be ideal for PLCs. I need to learn
ladder programming. On the web, there are plenty of tutorials but everything I've seen or tried is lacking in translating the
real-life process into a program. Any direction I should look? A lot of my stuff is old and doesn't have schematics yet alone a
flow chart. The guy I had that was very good at this retired and moved to SC.

"Steve Lusardi" wrote in message
...
PLCs only make sense when you have sequential events that are dependent on
previous events, like motion fault detection. From what I have gleaned
from previous postings is that your equipment is mechanically timed. In my
humble opinion I would concentrate on using electronic trigger technology,
solid state relays and motion validation logic (feedback). The value of
doing this is first reliability and secondly immediate system fault
identification. You should be able to use a common family of components
for all your solutions.
Steve


Thanks! I have different kinds of equipment for different families of
products. Most of my latest posts have been for mechanical equipment. The
other equipment I'm addressing is all hydraulic and pneumatic actuated. The
relay logic controls the valves.

"Buerste" wrote in message
...
I want/need to replace a few relay-logic controls with PLCs. Typically, a
machine is using 6 to 8, 3 or 4 pole DT relays, 6 to 8 limit switches and 3
to 4 operator switches, and 4 to 6 hydraulic/pneumatic valves. Should be
ideal for PLCs. I need to learn ladder programming. On the web, there are
plenty of tutorials but everything I've seen or tried is lacking in
translating the real-life process into a program. Any direction I should
look? A lot of my stuff is old and doesn't have schematics yet alone a
flow chart. The guy I had that was very good at this retired and moved to
SC.


man I hear ya. I used to do A LOT of this stuff. The real key is learning
exactly how your machine is working. It can be written up in ladder logic
form. I doubt you'll find a tutorial on this. It takes that right
combination of person that knows machines and has a lot of PLC programming
already under his belt.

I was never a ladder logic writer type. But, i could read and follow it if
the programmer walked me through it. So, my approach was to really watch the
machine and understand it. Write it all down in english. Then double check
the ladder BEFORE taking the machine apart and installing the PLC.

I'm sure you understand your machines. I'd suggest you hire a fella to
interview you and write the ladder logic of what you're got. keying it into
the PLC is trivial by comparison.

karl

"Buerste" fired this volley in
:

I want/need to replace a few relay-logic controls with PLCs.
Typically, a machine is using 6 to 8, 3 or 4 pole DT relays, 6 to 8
limit switches and 3 to 4 operator switches, and 4 to 6
hydraulic/pneumatic valves. Should be ideal for PLCs. I need to
learn ladder programming. On the web, there are plenty of tutorials
but everything I've seen or tried is lacking in translating the
real-life process into a program. Any direction I should look? A lot
of my stuff is old and doesn't have schematics yet alone a flow chart.
The guy I had that was very good at this retired and moved to SC.



IF you decide to use a PLC to do this, you can ease your task by choosing
one of the types of controller that incorporates a crippled BASIC or
BASIC-like programming language that can run behind the ladder.

Ladder logic is pretty foreign stuff to someone not schooled in thinking
in those terms. It becomes a lot easier for some, if the only things the
ladder code has to do is detect conditions, and the actual control is
done with a more-or-less easy to understand algorithmic language.

I do quite complex hydraulic/pneumatic systems around PLCs; The typical
machine has as many as thirty or forty limit and cycle sensing
conditions, and fifteen or more directional or proportional control
valves. In that sort of environment having a programming language
available is a boon. (even if I did have to write my own floating-point
library to support the app in an integer-only operating system).


LLoyd

Please remember that if you use solid state relays to drive inductive loads, always use R/C filters across AC loads and back EMF
diodes across DC driven loads.
Steve

"Buerste" wrote in message ...

"Steve Lusardi" wrote in message ...
PLCs only make sense when you have sequential events that are dependent on previous events, like motion fault detection. From
what I have gleaned from previous postings is that your equipment is mechanically timed. In my humble opinion I would
concentrate on using electronic trigger technology, solid state relays and motion validation logic (feedback). The value of
doing this is first reliability and secondly immediate system fault identification. You should be able to use a common family
of components for all your solutions.
Steve


Thanks! I have different kinds of equipment for different families of products. Most of my latest posts have been for
mechanical equipment. The other equipment I'm addressing is all hydraulic and pneumatic actuated. The relay logic controls the
valves.

On Jun 14, 1:04*am, "Buerste" wrote:
I want/need to replace a few relay-logic controls with PLCs. *Typically, a
machine is using 6 to 8, 3 or 4 pole DT relays, 6 to 8 limit switches and 3
to 4 operator switches, and 4 to 6 hydraulic/pneumatic valves. *Should be
ideal for PLCs. *I need to learn ladder programming. *On the web, there are
plenty of tutorials but everything I've seen or tried is lacking in
translating the real-life process into a program. *Any direction I should
look? *A lot of my stuff is old and doesn't have schematics yet alone a flow
chart. *The guy I had that was very good at this retired and moved to SC.

I learned by designing controls with actual relays before PLCs came
out. We didn't document other than the schematic, designers and
repairmen were expected to stare at it until it all made sense. Once I
understood 3-wire control (latching relays) the rest wasn't too bad.

This is another approach to understanding event-driven process flow:
http://en.wikipedia.org/wiki/State_diagram

jsw

Jim Wilkins fired this volley in
:

On Jun 14, 1:04*am, "Buerste" wrote:
I want/need to replace a few relay-logic controls with PLCs.
*Typically
, a
machine is using 6 to 8, 3 or 4 pole DT relays, 6 to 8 limit switches
and
3
to 4 operator switches, and 4 to 6 hydraulic/pneumatic valves.
*Should
be
ideal for PLCs. *I need to learn ladder programming. *On the web, the
re are
plenty of tutorials but everything I've seen or tried is lacking in
translating the real-life process into a program. *Any direction I
shou
ld
look? *A lot of my stuff is old and doesn't have schematics yet alone
a
flow
chart. *The guy I had that was very good at this retired and moved to
S
C.

I learned by designing controls with actual relays before PLCs came
out. We didn't document other than the schematic, designers and
repairmen were expected to stare at it until it all made sense. Once I
understood 3-wire control (latching relays) the rest wasn't too bad.

This is another approach to understanding event-driven process flow:
http://en.wikipedia.org/wiki/State_diagram

jsw


Another way one can learn is by purchasing a low-cost PLC and using the
associated tools.

One family of boards that comes with a compiler and hundreds of
programming examples is the TriLogic M-series.

Buy an 8x8 (8 in, 8 out) or a 16x16, and you'll have all the power you'd
likely need for such a project, along with all the tools and examples to
use the device. This series (as do others like it in other
manufacturers' catalogs) has PWM and Stepper control routines either
built-in or as free libraries. You don't even need a stepper controller,
just drivers. The board can handle it all in real-time while running
your application.

http://www.tri-plc.com/products.htm

Look at the M-series for high-power capabilities; all the way down to the
Nano and E-series for smaller aps.

I have a number of these in hot, humid environments. The oldest is over
6 years running now, with never a down moment due to hardware breakdowns.
(a few programming bugs, yes G)

LLoyd

On 6/14/2010 1:04 AM, Buerste wrote:
I want/need to replace a few relay-logic controls with PLCs. Typically, a
machine is using 6 to 8, 3 or 4 pole DT relays, 6 to 8 limit switches and 3
to 4 operator switches, and 4 to 6 hydraulic/pneumatic valves. Should be
ideal for PLCs. I need to learn ladder programming. On the web, there are
plenty of tutorials but everything I've seen or tried is lacking in
translating the real-life process into a program. Any direction I should
look? A lot of my stuff is old and doesn't have schematics yet alone a flow
chart. The guy I had that was very good at this retired and moved to SC.


Where are you located? I do this regularly with pneumatic systems.

On Jun 14, 1:32*pm, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:
Jim Wilkins fired this volley :





On Jun 14, 1:04 am, "Buerste" wrote:
I want/need to replace a few relay-logic controls with PLCs.
Typically
, a
machine is using 6 to 8, 3 or 4 pole DT relays, 6 to 8 limit switches
and
*3
to 4 operator switches, and 4 to 6 hydraulic/pneumatic valves.
Should
be
ideal for PLCs. I need to learn ladder programming. On the web, the
re are
plenty of tutorials but everything I've seen or tried is lacking in
translating the real-life process into a program. Any direction I
shou
ld
look? A lot of my stuff is old and doesn't have schematics yet alone
a
*flow
chart. The guy I had that was very good at this retired and moved to
S
C.

I learned by designing controls with actual relays before PLCs came
out. We didn't document other than the schematic, designers and
repairmen were expected to stare at it until it all made sense. Once I
understood 3-wire control (latching relays) the rest wasn't too bad.

This is another approach to understanding event-driven process flow:
http://en.wikipedia.org/wiki/State_diagram

jsw

Another way one can learn is by purchasing a low-cost PLC and using the
associated tools.

One family of boards that comes with a compiler and hundreds of
programming examples is the TriLogic M-series.

Buy an 8x8 (8 in, 8 out) or a 16x16, and you'll have all the power you'd
likely need for such a project, along with all the tools and examples to
use the device. *This series (as do others like it in other
manufacturers' catalogs) has PWM and Stepper control routines either
built-in or as free libraries. *You don't even need a stepper controller,
just drivers. *The board can handle it all in real-time while running
your application.

http://www.tri-plc.com/products.htm

Look at the M-series for high-power capabilities; all the way down to the
Nano and E-series for smaller aps.

I have a number of these in hot, humid environments. *The oldest is over
6 years running now, with never a down moment due to hardware breakdowns. *
(a few programming bugs, yes G)

LLoyd- Hide quoted text -

- Show quoted text -

One of the best methods I have found to create a ladder logic program
from a "new to me" machine is to create a series of "IF ... THEN ..."
sentences on a piece of paper. For example:

IF "Spindle Start" button is pushed AND "Spindle is not running" THEN
"turn on spindle motor"
IF "Spindle is Running" AND "Spindle Stop" button is pushed THEN "turn
off spindle motor"

These types of statements will export very easily to ladder logic
diagrams. Keep in mind, these are the basics of PLC programming.
There is a world of additional functions that modern PLCs offer...
timers/leading-edge events/trailing-edge events/serial IO

_kevin

On Mon, 14 Jun 2010 18:52:17 -0400, Wes
wrote:

karchiba wrote:

One of the best methods I have found to create a ladder logic program
from a "new to me" machine is to create a series of "IF ... THEN ..."
sentences on a piece of paper. For example:


I tend to use a steping form of logic as in equ 10 then this rung is active and when it is
satisfied there is a move command to move the stepper control value to step 20 or so.
Gotta leave room for the unexpected additions to logic.

That takes a little more planning up front, but for machines with
synchronous motions it makes debug much easier, and is easy to follow
when you come back to make a change six months later. I haven't
touched a Mitsubishi PLC in a long time, but they had a family of
functions they called "step-ladder" that made that style of
programming very convenient.

--
Ned Simmons

"Karl Townsend" wrote in message
anews.com...

"Buerste" wrote in message
...
I want/need to replace a few relay-logic controls with PLCs. Typically, a
machine is using 6 to 8, 3 or 4 pole DT relays, 6 to 8 limit switches and
3 to 4 operator switches, and 4 to 6 hydraulic/pneumatic valves. Should
be ideal for PLCs. I need to learn ladder programming. On the web, there
are plenty of tutorials but everything I've seen or tried is lacking in
translating the real-life process into a program. Any direction I should
look? A lot of my stuff is old and doesn't have schematics yet alone a
flow chart. The guy I had that was very good at this retired and moved to
SC.


man I hear ya. I used to do A LOT of this stuff. The real key is learning
exactly how your machine is working. It can be written up in ladder logic
form. I doubt you'll find a tutorial on this. It takes that right
combination of person that knows machines and has a lot of PLC programming
already under his belt.

I was never a ladder logic writer type. But, i could read and follow it if
the programmer walked me through it. So, my approach was to really watch
the machine and understand it. Write it all down in english. Then double
check the ladder BEFORE taking the machine apart and installing the PLC.

I'm sure you understand your machines. I'd suggest you hire a fella to
interview you and write the ladder logic of what you're got. keying it
into the PLC is trivial by comparison.

karl



One of my engineer's brother's next-door-neighbor's cousin's buddy does this
all the time and sells the hardware too. I'll just look over his shoulder
and go for the osmosis method.

"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message
. 3.70...
"Buerste" fired this volley in
:

I want/need to replace a few relay-logic controls with PLCs.
Typically, a machine is using 6 to 8, 3 or 4 pole DT relays, 6 to 8
limit switches and 3 to 4 operator switches, and 4 to 6
hydraulic/pneumatic valves. Should be ideal for PLCs. I need to
learn ladder programming. On the web, there are plenty of tutorials
but everything I've seen or tried is lacking in translating the
real-life process into a program. Any direction I should look? A lot
of my stuff is old and doesn't have schematics yet alone a flow chart.
The guy I had that was very good at this retired and moved to SC.



IF you decide to use a PLC to do this, you can ease your task by choosing
one of the types of controller that incorporates a crippled BASIC or
BASIC-like programming language that can run behind the ladder.

Ladder logic is pretty foreign stuff to someone not schooled in thinking
in those terms. It becomes a lot easier for some, if the only things the
ladder code has to do is detect conditions, and the actual control is
done with a more-or-less easy to understand algorithmic language.



I just suggested one of these somewhere elsa on the group. They are pretty
cheap and are programmed in a sort of Basic like language
http://www.splatco.com/controllers.htm

I do quite complex hydraulic/pneumatic systems around PLCs; The typical
machine has as many as thirty or forty limit and cycle sensing
conditions, and fifteen or more directional or proportional control
valves. In that sort of environment having a programming language
available is a boon. (even if I did have to write my own floating-point
library to support the app in an integer-only operating system).


LLoyd

On Tue, 15 Jun 2010 07:56:31 -0700, Larry Jaques
wrote:

On Tue, 15 Jun 2010 03:26:42 -0400, "Buerste"
wrote the following:


"Karl Townsend" wrote in message
ctanews.com...
I'm sure you understand your machines. I'd suggest you hire a fella to
interview you and write the ladder logic of what you're got. keying it
into the PLC is trivial by comparison.

One of my engineer's brother's next-door-neighbor's cousin's buddy does this
all the time and sells the hardware too. I'll just look over his shoulder
and go for the osmosis method.

Yeah, shouldn't take more than a couple minutes.

Ladder is probably the right language for your job, but I've
programmed plc's in function block diagrams, structured text (like
basic or pascal), and sequential function charts. I used ladder the
least.

Pete Keillor

On 6/14/2010 7:29 PM, Buerste wrote:
wrote in message
...
On 6/14/2010 1:04 AM, Buerste wrote:
I want/need to replace a few relay-logic controls with PLCs. Typically,
a
machine is using 6 to 8, 3 or 4 pole DT relays, 6 to 8 limit switches and
3
to 4 operator switches, and 4 to 6 hydraulic/pneumatic valves. Should be
ideal for PLCs. I need to learn ladder programming. On the web, there
are
plenty of tutorials but everything I've seen or tried is lacking in
translating the real-life process into a program. Any direction I should
look? A lot of my stuff is old and doesn't have schematics yet alone a
flow
chart. The guy I had that was very good at this retired and moved to SC.


Where are you located? I do this regularly with pneumatic systems.

I'm in Cleveland.


Bummer. I'm in Lapeer, MI. Too far for a daily commute.

"syoung" wrote in message
news
On 6/14/2010 7:29 PM, Buerste wrote:
wrote in message
...
On 6/14/2010 1:04 AM, Buerste wrote:
I want/need to replace a few relay-logic controls with PLCs.
Typically,
a
machine is using 6 to 8, 3 or 4 pole DT relays, 6 to 8 limit switches
and
3
to 4 operator switches, and 4 to 6 hydraulic/pneumatic valves. Should
be
ideal for PLCs. I need to learn ladder programming. On the web, there
are
plenty of tutorials but everything I've seen or tried is lacking in
translating the real-life process into a program. Any direction I
should
look? A lot of my stuff is old and doesn't have schematics yet alone a
flow
chart. The guy I had that was very good at this retired and moved to
SC.


Where are you located? I do this regularly with pneumatic systems.

I'm in Cleveland.


Bummer. I'm in Lapeer, MI. Too far for a daily commute.

Unless you drive like my girlfriend!

Ned Simmons wrote:

That takes a little more planning up front, but for machines with
synchronous motions it makes debug much easier, and is easy to follow
when you come back to make a change six months later. I haven't
touched a Mitsubishi PLC in a long time, but they had a family of
functions they called "step-ladder" that made that style of
programming very convenient.

My plc experience has been limited to the allen bradley world. PLC2, SLC150, PLC500. We
are using something called RSLogix 5000 now. I'm not sure I like it that much but it has
neat things like a SQL interface stuck in a slot so it isn't all bad. I think that is
called an Xcoupler.

Looking for simple inputs and outputs is a bitch though. I'm used to being able to see
slots in a rack. No training so maybe I'm missing something. Just see a bunch of tags. I
tend to look at prints and open the cabinets and trays where the flex IO is located to see
what is happening when troubleshooting.

Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller

On 06/13/2010 10:04 PM, Buerste wrote:
I want/need to replace a few relay-logic controls with PLCs.

(snip)

The guy I had that was very good at this retired and moved to SC.

A bell just went "bing!" in my head -- do you need to find a smart kid
who can make this happen under direction? I.e., if you can't _find_ the
person to do the job, can you _make_ one?

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

"Buerste" wrote in message
...
I want/need to replace a few relay-logic controls with PLCs. Typically, a
machine is using 6 to 8, 3 or 4 pole DT relays, 6 to 8 limit switches and 3
to 4 operator switches, and 4 to 6 hydraulic/pneumatic valves. Should be
ideal for PLCs. I need to learn ladder programming. On the web, there are
plenty of tutorials but everything I've seen or tried is lacking in
translating the real-life process into a program. Any direction I should
look? A lot of my stuff is old and doesn't have schematics yet alone a
flow chart. The guy I had that was very good at this retired and moved to
SC.


There is a program called logixpro

http://thelearningpit.com/lp/logixpro.html

You can download the demo version and program and test ladder logic for
free. The program is like Allen Bradley RSlogix 500 programming software.
It's a cheap way to learn this stuff, unfortunately the actual Allen Bradley
software isn't that cheap.

You need to decide what PLC's to go with because the learning and software
will probably be a larger investment than the hardware that you can probably
find on eBay.

Years ago Mitsubishi electric was clearing out some of their older controls
and I bought a few of them on eBay, they came with programming software.
What you have to decide includes do you want 24V DC or 120V AC power to PLC,
input voltage, output voltage. Do you have any PLC programming software
available now? Relay outputs will work with 24V DC or 120V AC but
mechanical relays have less life than solid state transistors (24VDC) or
SCR/Triacs(120VAC).

I kind of like 24VDC for inputs and 120VAC for outputs, this gives you high
speed for inputs and more output power to drive valves, etc. For example,
if you have an output card current rating of 2A, that would be up to 48
Watts DC or up to 240 Watts AC for the same current, can help if you're
driving multiple valves.

If you decide on a PLC I can help you through getting the program to do
whatever you want it to. One of the cheapest to get working PLC's is the
Automation Direct PLC, but I'm not sure on their quality, not sure if you
would be better off with Automation Direct or something else.

The modular racks are nice because you can get cards for whatever you want,
you can have some AC and some DC input and output cards as you need. If you
use a fixed I/O PLC you could use relays to convert between the AC and DC
in's and out's.

RogerN

On Tue, 15 Jun 2010 18:55:34 -0400, syoung wrote:

On 6/14/2010 7:29 PM, Buerste wrote:
wrote in message
...
On 6/14/2010 1:04 AM, Buerste wrote:
I want/need to replace a few relay-logic controls with PLCs. Typically,
a
machine is using 6 to 8, 3 or 4 pole DT relays, 6 to 8 limit switches and
3
to 4 operator switches, and 4 to 6 hydraulic/pneumatic valves. Should be
ideal for PLCs. I need to learn ladder programming. On the web, there
are
plenty of tutorials but everything I've seen or tried is lacking in
translating the real-life process into a program. Any direction I should
look? A lot of my stuff is old and doesn't have schematics yet alone a
flow
chart. The guy I had that was very good at this retired and moved to SC.


Where are you located? I do this regularly with pneumatic systems.

I'm in Cleveland.


Bummer. I'm in Lapeer, MI. Too far for a daily commute.


Hows the weather in Lapeer?

Gunner, formally from the UP and Grayling


One could not be a successful Leftwinger without realizing that,
in contrast to the popular conception supported by newspapers
and mothers of Leftwingers, a goodly number of Leftwingers are
not only narrow-minded and dull, but also just stupid.
Gunner Asch

On Tue, 15 Jun 2010 20:38:27 -0400, Wes
wrote:

Ned Simmons wrote:

That takes a little more planning up front, but for machines with
synchronous motions it makes debug much easier, and is easy to follow
when you come back to make a change six months later. I haven't
touched a Mitsubishi PLC in a long time, but they had a family of
functions they called "step-ladder" that made that style of
programming very convenient.

My plc experience has been limited to the allen bradley world. PLC2, SLC150, PLC500. We
are using something called RSLogix 5000 now. I'm not sure I like it that much but it has
neat things like a SQL interface stuck in a slot so it isn't all bad. I think that is
called an Xcoupler.

Looking for simple inputs and outputs is a bitch though. I'm used to being able to see
slots in a rack. No training so maybe I'm missing something. Just see a bunch of tags. I
tend to look at prints and open the cabinets and trays where the flex IO is located to see
what is happening when troubleshooting.

Wes

I much preferred tags. Having to use a physical address everywhere in
the programming kept me from adopting plc's for quite a while. The
mapping of tag to physical address happens at tag definition usually,
although not always. I had occasion to use a fair bit of repetive
programming, lots of similar pumps, etc. Tags made it easy. Just
copy, paste, change the physical address. I did a fair bit of control
stuff, but it wasn't my main job. Now that I'm retired, I don't
expect I'll be doing that again.

Pete

Pete Keillor wrote:

I much preferred tags. Having to use a physical address everywhere in
the programming kept me from adopting plc's for quite a while. The
mapping of tag to physical address happens at tag definition usually,
although not always. I had occasion to use a fair bit of repetive
programming, lots of similar pumps, etc. Tags made it easy. Just
copy, paste, change the physical address. I did a fair bit of control
stuff, but it wasn't my main job. Now that I'm retired, I don't
expect I'll be doing that again.

Oh, I never used physical addresses except back when I was using a hand held programmer
for a SLC 100 or 150 and some other ancient thing.

As soon as I was using PC based programming software, I used symbolic addressing so I:1/2
was refered to as UP_PB (up push button). Much easier to program that way. To a degree
with good symbols the code tended to be self documenting.

I've run into machines where the original ladder files with all the nice comments and such
couldn't be found. I end up plugging in, grabbing a current processor image and then
determine what various buttons, switches and coils do and start using symbols to name them
in the ladder so I can form a mental picture of what is going on.

Wes

On 6/15/2010 10:57 PM, Gunner Asch wrote:


Bummer. I'm in Lapeer, MI. Too far for a daily commute.


Hows the weather in Lapeer?

Gunner, formally from the UP and Grayling



Actually quite nice right now. Where in the U.P.? I co-own 40 acres with
my brother in Seney. A Seney neighbor lives in Gaylord.

On Wed, 16 Jun 2010 17:33:06 -0400, syoung wrote:

On 6/15/2010 10:57 PM, Gunner Asch wrote:


Bummer. I'm in Lapeer, MI. Too far for a daily commute.


Hows the weather in Lapeer?

Gunner, formally from the UP and Grayling



Actually quite nice right now. Where in the U.P.? I co-own 40 acres with
my brother in Seney. A Seney neighbor lives in Gaylord.

Ah yes..the Seney Stretch..the worst place I ever picked to hitchhike in
Febuary.

I grew up in Hancock and Calumet, wound up in Grayling at the age of 14,
graduated from there.

Most of my family are Yoopers, many of who flocked to Detroit for the
war, but many stayed in the Copper Country.

Gunner
One could not be a successful Leftwinger without realizing that,
in contrast to the popular conception supported by newspapers
and mothers of Leftwingers, a goodly number of Leftwingers are
not only narrow-minded and dull, but also just stupid.
Gunner Asch

"Buerste" wrote in message
...
I want/need to replace a few relay-logic controls with PLCs. Typically, a
machine is using 6 to 8, 3 or 4 pole DT relays, 6 to 8 limit switches and 3
to 4 operator switches, and 4 to 6 hydraulic/pneumatic valves. Should be
ideal for PLCs. I need to learn ladder programming. On the web, there are
plenty of tutorials but everything I've seen or tried is lacking in
translating the real-life process into a program. Any direction I should
look? A lot of my stuff is old and doesn't have schematics yet alone a
flow chart. The guy I had that was very good at this retired and moved to
SC.


Give an example of what you want to make a machine do and I and/or others
can provide logic. Take it step by step, don't describe the whole operation
but just the first step. We can provide sample code to perform the step and
you can understand how each step works, and apply it to your machines
however you need to.

For example, it is common to have a run mode for a machine that is enabled
when you press a "Start" pushbutton and latched in until you press the
"STOP" button or an E-stop, safety switch, or any sort of interlock is
broke. For this you normally wire through contacts so that power is made to
the input so the input is ON when it is in the safe condition, that way, if
a wire is broke in the safety circuit, the thing stops running.

START STOP RUN
|----| |----|----| |-----( )--|
| |
| RUN |
|----| |----|

This says if the start button is pressed while the stop input is on (safe to
run) then the run memory comes on. Once the run memory comes on it branches
the start button so the start button doesn't have to be held in.


Then you might have something like this:

RUN AUTO_SS AUTO_MODE
|----| |----|----| |---------( )--|
|
| AUTO_SS MANUAL_MODE
|----|\|---------( )--|


OK, then you might have a rung telling when everything is in home position,
perhaps the initial position needed for all system go, ready to start. If
it is in auto mode and homed, then it can run the automatic cycle. If it is
manual position it can be homed with a home button or operated manually as
needed.

The cycle normally involves a step and detecting when that step is done,
often a dwell timer before the next step starts. Eventually this gets back
to the position to start the next cycle and it is repeated. You can have a
condition for a "Stop at the end of the cycle" to stop the machine without
crashing the current cycle. At the end of the automatic cycle, it checks
"Stop at end of cycle" and stops or continues operation.

I would recommend just starting to update a machine and ask questions when
they arise, it seems there are plenty of people on here knowledgeable and
willing to help. Once you get walked through one machine you can probably
get through 95% of the next machine before you run into something you have a
question on.

If you know the machine and you know the program, you will be able to modify
it for better performance or upgrade the automation, such as interface it to
work with an automatic feeder or robots and such.

RogerN

On Jun 15, 2:34*am, "Grumpy" wrote:
"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in messagenews:Xns9D97494D258F8lloydspmindspringcom@2 16.168.3.70...





"Buerste" fired this volley in
:

I want/need to replace a few relay-logic controls with PLCs.
Typically, a machine is using 6 to 8, 3 or 4 pole DT relays, 6 to 8
limit switches and 3 to 4 operator switches, and 4 to 6
hydraulic/pneumatic valves. *Should be ideal for PLCs. *I need to
learn ladder programming. *On the web, there are plenty of tutorials
but everything I've seen or tried is lacking in translating the
real-life process into a program. *Any direction I should look? *A lot
of my stuff is old and doesn't have schematics yet alone a flow chart.
*The guy I had that was very good at this retired and moved to SC.

IF you decide to use aPLCto do this, you can ease your task by choosing
one of the types of controller that incorporates a crippled BASIC or
BASIC-like programming language that can run behind the ladder.

Ladder logic is pretty foreign stuff to someone not schooled in thinking
in those terms. *It becomes a lot easier for some, if the only things the
ladder code has to do is detect conditions, and the actual control is
done with a more-or-less easy to understand algorithmic language.

I just suggested one of these somewhere elsa on the group. They are pretty
cheap and are programmed in a sort of Basic like languagehttp://www.splatco.com/controllers.htm





I do quite complex hydraulic/pneumatic systems around PLCs; *The typical
machine has as many as thirty or forty limit and cycle sensing
conditions, and fifteen or more directional or proportional control
valves. *In that sort of environment having a programming language
available is a boon. (even if I did have to write my own floating-point
library to support the app in an integer-only operating system).

LLoyd- Hide quoted text -

- Show quoted text -- Hide quoted text -

- Show quoted text -

I down loaded their help demo tuturial, and got the non working
software. Wow, this was too cool.
Does any other vendor have this simple of a ladder logic coding
software, I never could figure out how to get the automation direct
demo to work.

The development kit, is a $300 with shipping, for the one with RTC, a
little pricy.
My first project is to take the manual surface grinder, and install
power feeds, and use a PLC to control the surface feed, and cross
step. The verticle is a little trickyer as you can't trust that a
tenth down, won't jump 2 thou, at least on this 6x12 HF.