There is no way to suppress these.

P007,008 and 009 are errors reported by the HMI, P499 is the HMI reporting an error it received from the Solo. P499 009 is a Checksum error. All of the errors point to a malformed packet.

Some suggestions:

1) Momentarily disconnection the PC from the RS-485 network and see if the PC really the cause. If the errors go away, check the echo suppression setting in the Micro and in the PC. In the C-more Micro project this is done by selecting RS-485 = Yes in the Panel Manager.

2) If the errors do not go away when you disconnect the PC, they are coming from somewhere else. I would suspect noise is getting on the RS-485 pair scrambling the packets. Is the cable shielded and grounded? Is it tie wrapped to a power cable or running in the same tray as a power cable? Try pulling it away from all other cables and see if the errors go away. That will tell you something. Try keying a radio in front of the cabinet. (Make sure nothing is running for safety reasons) If it causes errors, then you may have a shielding/grounding problem.

Thanks for the info. I tried disconnecting the PLC board from the RS-485. The red/black wires go to the EA3 and the white/green are for the existing PLC board.

This stopped all the error messages. The HMI was able to display the data from the SOLO and also write a new setpoint.

The problem is, I can't leave the PLC board disconnected. The operator uses the old HMI too. The idea this new HMI is to make things easier for them so they can monitor and adjust temperature from either side of the machine.

In the C-more micro software, I already have "Select RS-485" set to Yes.

As far as the cabling goes, it has an overall foil shield with a drain wire that I have one end connected to pin 1 on the DB-15 as follows:

It does run along the 120VAC power for the temperature controller for a couple feet along the back of the cabinet door (this was a retro-fit that I was trying to get done while the operators were on break) but the current through those wires is minimal, and it did work without errors while I had that PLC board disconnected from the RS-485.

It loos like you have the PC wires also with that power wires also. If I am seeing that correctly that may be where the noise is coming in. I'd unbundle everything and keep the PC connected and see what happens.

Does the PC RS-485 cable have a shielded cable that is grounded on one end?

Also, make sure the Micro has a good ground. You are depending on that to drain the shield on the cable.

Hi @Keystone Shawn (Customer)​ 

So the errors are caused by the other Master (PC) communicating to the Solo at the same time as the C-More Micro Master on the network.

This is not recommended for Modbus RTU. There should only be one master and several slaves on the same network.

You could try to change your poll time on the C-More. Hopefully, you can get lucky and pick a frequency that does not match the other PC.

You could replace the other Master (PC) with another C-More and Small PLC like a Click. The two C-More Microcontrollers communicating Ethernet to the Click. The Click would then communicate Modbus RS485 to the Solo.

Just a thought.

Regards,

Garry

https://accautomation.ca/click-plc-send-and-receive-instructions/

https://accautomation.ca/series/click-plc/

https://accautomation.ca/series/c-more-micro-hmi/

Hi Gary. Thank you for your reply. Yeah, that's what I was afraid of.

A little background... The reason the first machine I did this on didn't have the pc board on the RS-485 is because that machine's HMI died. The board is still running some basic I/O functions on the machine, but since it could no longer display the temperature and allow for setpoint changes, I removed that wiring when I added in the c-more. It was also communicating on the RS-485 with a Yaskawa VFD to allow for speed changes, but I put in a pot. to handle that as a temporary measure.

So I guess the next step is replacing that pc board on the first machine, then when that's all working I can duplicate the results on the 2nd machine. BTW, I've used a few Clicks here already and really like them. I've been dragging my feet on this because the cabinet in the first machine is an absolute mess.

My predecessor also didn't document anything, so it's probably best eliminate all the old stuff anyway since we don't even have the software for it. I've got a plan now. Thanks again for the help.