teamwork on PLC systems

Bit Smith

Member
Join Date
Jun 2018
Location
MX
Posts
2
Hi,

Is there any philosiphy or design pattern to develop PLC programs in a colaborative way (various engineers working on a different aspect of the same plc program?).
 
Welcome to the forum!

I would say there is no one true pattern, but it is definitely helpful to use a pattern if multiple people will be developing a program.

Are the engineers all working for the same company at the same facility? If so, then you or the head engineer can make the rules. If this is in a customer/manufacturer relationship, then the situation becomes a bit more challenging but I would advise reaching an agreement on the rules before the programming begins.

If you tell folks here which PLC/software you are working with, they may be able to provide some guidelines specific to that product.
 
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the first thing I would do is have a meeting and discuss what is needed in regards to timers, counters, bits, words, subroutines,and so on.

then set up a map.
the end user (you) would then draw up the map for everyone and add spares for everything.
you then assign each programmer his addresses and SPECIFY they cannot go outside that range without your approval, and then you would assign them more addresses.

the trouble with that is, you really don't know what you need until the programming is almost complete.

then you have to worry about plc memory availiability, on line edits,
james
 
I don't work with projects big enough to have multiple concurrent programmers on one PLC.

however what I've done before when I've been busy is assigned certain tasks to other guys. Like "take section 3.1 of the spec and write me a polymer dosing skid control block". They then send me a DFB or AOI depending on platform (we're Schneider and Rockwell only), and I then import it into my main application.

Im sure there are other more sophisticated ways too.
 
Yes, we do it by adhering to an established programming standard. In my case the standard is set by the HQ engineering team, and we techs are expected to adhere to it. We have a programming standard for just about everything, motor logic, valve logic, PID, tag names...the standard is well documented and extensive.
 
Hi.
Thanks a lot for your response.
Answering to what RonJohn points, Yes,
- We're all working for the same company
- We are able to set rules of development.
- About the brands, we develop mostly in Siemens/Allen Bradley.

Regarding iraiam, so far we've tried to define a standard behavior for the elements we use (mostly valves, motors, flow and temp sensors).

Then, from what I can understand the key point to this might be:

-Use a well defined standard.
to have common behavior in different systems but same element (e.g. valve in skid and valve in dosifier)

-define tag sets or memory regions per system and HW specifics requierements (timers, counters, bits, etc)
Where each programmers should be bound.

-have well defined interfaces for system level blocks (e.g. skids)
to connect each programmers job to a main program.


Finally, and connected to this topic (if I should open another thread please indicate it),
Do you know or advise to use a versioning system to work with plc programs?.

Regards,
Bit Smith
 
Bigger projects sharing a single PLC (or multiple PLCs sharing the same I/O) are typically broken by station or function. I'm coming off a project that had multiple cells, each with one PLC, each cell had multiple stations and multiple robots performing the material handling.

For each cell, one engineer was assigned to the stations, and one for the material handling between the stations (conveyors and robots). Besides the PLC, the other device that could be programmed by more than one was the HMI. Common elements (standards) for the PLC, station interlocks, and HMI screens were agreed on and used across the whole project.

A total of four cells and four engineers were involved and responsibilities were different per cell. I drew the material handling straw on all of the cells because of the robots and on one cell with just a few stations I did double duty. it all depends on the project timing and complexity how responsibilities were handed out.

It helps that everyone has worked together previously so that programming styles are for the most look and act the same. Its understood that agreed upon "standards", over and above the customer's, are strictly followed.

I did daily backups and each program name had the date appended as a suffix. Pretty simple.
 

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