Modbus TCP Illegal data address error from Micro820 to Red Lion Graphite HMI

JeffreyS · Jul 15, 2016

I have the HMI setup as shown in the picture. Then from my PLC and from the handy Baseblock ComTest Pro program I get a illegal data address. "
Any ideas what the trick is here to make this work. I have the tag TagForPLC1toCheck set to True so I should get back a 1 when I read that first single coil bit.
( sorry for the null post below )

nhatsen · Jul 15, 2016

The first image (HMI.jpg) is too blurry and it's difficult to read the configuration.

According to the second image, you'are tryng to read a register from the HMI (PLC is master modbus). Is it correct?

JeffreyS · Jul 15, 2016

Added a zoomed in pic that is more clear.

JeffreyS · Jul 15, 2016

I am setting the protocol in the HMI to a Modbus TCP/IP slave so this should allow us to read that bit. Yes the PLC is a master.

nhatsen · Jul 15, 2016

I know the Direction parameter (Device to G3) works when you want to write from the PLC to HMI. I'm not sure if it's the same setup when you want to read (I don't have a manual to check that).

What modbus fuction are you using?

JeffreyS · Jul 15, 2016

https://www.seltrol.com/services/application-blog/57-collecting-data-from-red-lion Yea I just changed that so it is a green block now, made it 40001 for a holding register and picked an int tag so it is a blue square like the one in the link. I download that and still stuck on illegal data address. The Baseblock program has Cmd of 3 so it should be reading the 4xxxx registers.

JeffreyS · Jul 15, 2016

The program example from that link works no problem. Not sure why it wont work for me. We can't upload code files here can we?

JeffreyS · Jul 15, 2016

In the file you can download from the site it works at device number 1. I deleted that device and added a Micro800 as device 1 then added the Modbus slave protocol so it gets set to device 2. Added everything back they way the example program had it so the only difference should be the device 2 vs 1. This then breaks the read. I can't read at 1 or device 2.

The problem must be that a Modbus TCP slave device MUST be set to 1. Can anyone else try and confirm this?

JeffreyS · Jul 15, 2016

This creates a big problem! My G15 Graphite even from a blank new file starts the first protocol at device 2!!!! This would never allow the HMI to be able to be read from over Modbus TCP because you can never get it to setup as device 1...

WTH TIMMYYYYYY

Modbus TCP Illegal data address error from Micro820 to Red Lion Graphite HMI

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