CommonWealth Scientific Corporation, Robot chamber

[jack17]

Hi all,
I'm a computer science grad student.
I'm currently working on this Robot Chamber, which is a product of CS corportaion.
At one stage, the open command click works and triggers the opening of a valve in the chamber. Whereas the closing doesnt work.

The sytem is developed with C programming.
I have no clue how to start working on thi problem.
Can anybody suggest me a way.

I can work on C programs, but i dont know..how to check the PLC's.
Is there any techinical advise available here from a person has an expertise in a similar domain.

Jack
NY

 

[Terry Woods]

If this is a "C-Program" running in a PLC... one way or another, you are going to have to get your hands on the "Source Code".

Once you do that, you can look into how the program works.

However... in order to fix anything in the code you'll need the appropriate C-Compiler. (Not all compilers are acceptable to all PLCs).

You'll probably need the particular PLC Software as well.

C-Code is great... if you have the source, and the proper compiler.

What kind of PLC is this?

 

[jack17]

its GE fanuc 90-30 series programmable controller.
yes i have the source code, the interface for the application is all written in C. But as i have not worked on communicating with the PLC from a C program, i was looking for advice on this area.
I'm trying to understand the program flow and have traced almost 80% of the flow , except that i'm stuck at the point where the PLC is made a contact in the program.
I see some thing in the code that the commands clicked from the interface, is stored in a shared memory. I believe the PLC should be reading this memory or so.(not sure).

Its not like I know nothing about it, even if i dont , i still persist to fix the problem.
All i wanted is some useful tips from the people experienced in this field.

jack
NY

 

[jstolaruk]

Have you tried contacting the CS Corporation or GE Fanuc?

 

[Steve Bailey]

Does the C application run on a PC and communicate with the PLC through a serial port, or is it a subroutine running as part of the PLC program?

If it's the latter, it's surprising that you have the source code. Generally when OEMs use C subroutines in the 90-30, it's to create proprietary code that can't be viewed or modified.

GE Fanuc sells a C developer's toolkit to OEMs to develop and compile executables for the PLC. It's quite expensive, and they make you jump through hoops before they'll sell it to you. Basically, they only want to sell it to experienced C programmers who are also very familiar with the operation of the PLC. If I remember correctly, they only offer a limited amount of time during which the tech support line will answer question related to its use. For assistance beyond that time, you have to send them a PO.

 

[OkiePC]

Does the close command work in other positions? Maybe there's a limit/prox switch or something that isn't making/breaking in the trouble position...

 

[jack17]

The C programs are in the PC. it communicates with the PLC through the serial port.
the open command works, and there are other operations that work.
The close button click doesnt do anything.
and if i go and manually close the valve, the PLC does indicate that valve is now closed.

????

no i havnt contacted the GE or CS people?
would that really help??

 

[jack17]

we have OS/2 and there is good use of this OS2.H,i the C programs.

 

[Steve Bailey]

Has this system ever worked correctly?

If you have the PLC programming software, you can monitor the PLC while you click the object in the C application that is supposed to command the valve to close. If clicking the object writes a '1' to the memory location, then the problem is somewhere else in the PLC ladder logic. If you click the object and the C application doesn't write to the correct memory location, then the problem is in the C application.

 

[jack17]

thanks steve,

i do have a plc prog s/w i.e LM90 series.
but that has a problem too. It is not able to communicate with the PLC's.

The sytem was working properly, before it was shipped to our lab.
PLC does indicate that open click was done and it doesnt indiacate when the close is clicked.
when we manually close the valve, the PLC does indicate that the valve is closed. we logically concluded that there is no problem with the PLC and the machine communication.

any suggestions on this??
Jack

 

[MarkTTU]

Look for the broken or loose wire. If it worked before it shipped and it doesn't work now then you've got a 99% chance that something got loose in shipping or didn't get put back together the same way.

 

[Steve Bailey]

How is the valve actuated? Is it a solenoid to open and another solenoid to close?

If the PLC is controlling the valve, then there is an output module involved. Output modules have LED indicators that tell you when the outputs are energized. You could click the object in the C application that is supposed to command the valve to open and close and watch the LEDs on the output module.

It's possible that the PLC is commanding the valve to close, but the output circuit is faulty. Some output modules have fuses. Output modules require an external power supply for the field devices (valves).

Lots of things that could be wrong. It's too bad that you can't get your programming software to communicate with your PLC. That would help your troubleshooting efforts. The programming port on a GE Fanuc 90-30 is 15-pin port on the power supply. It is RS418, so you need a RS232/RS485 converter to be able to communicate from you computer. Your computer also needs to have a serial port. If it doesn't have one, you also need a USB/serial converter.

 

[jack17]

The computer does has a serial port.There is this cable connecting from back of the computer to the PLC, at the PLC end its a 25 pin,

and at the computer end its a 15 pin.

Can we run LM90 with the current setup of the system.Both the COM ports 1 and 2 are connected to the PLC processors,2 of them.

jack

 

[Steve Bailey]

Now there are two PLCs?

I've never run across a PC with a 15-pin serial port, but every 90-30 has a 15-pin programming port on the power supply. What are you plugging the 25-pin end of the cable into on the PLC? Is there a serial communications module (IC693CMM311) involved?

How about drawing a sketch of your system and attaching it to your next post.

Typical connection between a PC running Logicmaster and a PLC is from the PC's COM1 or COM2 port to the 15-pin port on the 90-30 power supply. This typically requires a RS232/RS485 converter, since most PC's COM ports are RS232. Power for the converter is supplied by the PLC. There is +5 VDC on pin 5 of the PLC's 15-pin port relative to pin 7.

If you need this system up and running quickly, you should hire a local integrator to help you troubleshoot it. Either that or try to get someone from the company that built the system or from your local distributor of GE Fanuc products to come in and help you out. I get the sense that you're in a bit over your head on this. That's not intended to be a commentary on your abiities, just that you haven't had enough experience with systems like this to recognize what's important when it comes to troubleshooting. You can continue to work through this forum, and I'll offer whatever help I can, but it's not the quickest way to get to the bottom of your problem.

 

[jack17]

the two cables run from the back of the computer's COM1 and COM2.

the other end of the cables , which are of 25 pins, is connected to the PCM 311 COPROC, and PCM 301 COPROC, respectively.

I'm attaching the software schematic diagram.

jack17