GE 90-30 to Eaton HMI via Serial Coproc

I have been asked to figure out why 2 HMI's will not work at the same time that are connected to a GE 90-30 rack with a 352 CPU. The HMI's are Eaton using the Canvas software with KepServer for communication. The communication is an RS232 link going into a 2 channel COMM COPROC module.

I have been told that each HMI will work alone, but if both are connected they will not work. My first thought was an address conflict. I quickly looked through the OPC settings but did not see any setting for an address. After I left there and did some research, it seems there are multiple protocol options that can be used and I did not get which one was being used.

Does anyone have any idea what could cause this not to work? I am scheduled to return to the plant on Wednesday to look at the machine again.

I recall that many years ago GE recommended not exceeding 9600 baud when using both ports simultaneously. You may need to slow down. To do so you will also need to modify the PLC's hardware configuration.

Another bit of information I was given is that the 2nd HMI was replaced with a newer model. Before the previous one went bad, they were both supposedly working simultaneously.

Could this be caused by a limitation of the KepServer driver? I do not know what HMI was originally in there, but it possibly did not use the KEPServer software for the driver.

Could this be caused by a limitation of the KepServer driver?

Click to expand...

The ports on the CMM311 module are independent of each other. You could set one port for the GE SNP protocol and the other one for Modbus. That makes me doubt that it's a limitation of the KepServer driver.

You said that both HMIs have successfully communicated separately. Have you tried both HMIs on both ports? Also, there is a white reset button on the CMM311 module behind the black cover. Try resetting after you have connected the second HMI.

There are two LEDs on the CMM311 module labeled US11 and US2. They blink when there is traffic on their respective serial port. Do see any occasional blinking on the the LED corresponding to the second HMI? That would indicate an attempt by the HMI to establish communication, but not getting a response from the PLC.

There are two serial ports on the CPU352 module. The fifteen pin port is RS485 and teh RJ11 port is RS232. You could try making a new cable and connecting one of the HMIs to that one.

This is very long shot based on the fact that both HMIs can communicate when only one is connected. I recall another quirk of the older firmware versions of Panel Mates. In the SNP protocol there is a SNP ID parameter similar in function to the Modbus ID parameter in the RTU protcol. The default setting for the 90-30 is no SNP ID, that is, a blank field for that parameter. Older Panel Mate versions defaulted to a SNP ID setting of zero. Zero is not the same thing as "blank" so those Panel Mates required the PLC's SNP ID be set to a non-blank value to match the HMI setting.

Thanks for the information. I am scheduled to go back to look at this machine again tomorrow, so I will check on these things.

I had done some more work on this, but still haven't been able to get the communications to work. I wired the ePro panel to port 1 of the communication card using RS-232 and that gave me a blink on the comm light every 1 second, which was the retry time of the KEPServer.

The original programmers are saying the comm card is configured for RS-485, but their cable supposedly wired for RS-485 does not even blink the comm light. My next trip there I will check their cable for proper wiring of RS-485

As for the one panel working at a time, they were not able to demonstrate that to me, so it appears that may not have been the case.

How is the comm card configured? Through the PLC programming software?

The CMM311 module is configured via the programming software. Port 1 is limited to RS232. Port 2 can be either RS232 or RS485. Make sure your HMI cables are connected to the proper port on the splitter cable coming out of the CMM311.

If they have a backup copy of the project file but lack the programming software to open it, post the backup here or email it to me at stephen dot bailey2 at verizon dot net. I'll check the configuration for you.