Setting up a digi one iap between controllogix(Ethernet) and modbus rtu temp controll

RNation0001

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Jun 2017
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kentucky
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Title says most of it. I have a thermon tcm2 heat Trace controller that is modbus rtu. It's hooked to a digione iap to which I have hooked to my stratix 8300 switch into a 5573 processor. I'm having zero luck getting this communicating with my plc. I setup a modbus tcp connection and can get the 4x 102 value that I'm wanting to display on the program avReporter modbus tester on my laptop but that's it. Can't seem to get the control logix talking. I tried the digione guides with no luck also. I then tried the modbus sample code from Rockwell to try to get it communicating through modbus tcp like the program on my PC uses but still have no luck. Anyone out there got any helpful advice to get this working. Thanks
 
I can’t help you with the Digi device, but I can point you to a much simpler way to move the data. Spectrum Control’s is about to release their new “Universal Gateway” which supports multiple protocols and will bridge EtherNet/IP to Modbus RTU. It’s configured via a web browser and is very easy to setup. You don’t have to do anything special in either PLC just simply setup the Gateway with the two PLC’s and the location of the data points (the Tags in the Logix PLC and the Modbus addresses in the RTU device).
https://www.spectrumcontrols.com/products/webport-solutions/universal-gateway/
 
I had a good experience with the digi one IAP. three different Control Logix PLCs reading 6 different modbus slaves all at the same time.


I can't remember the specifics of the setup other than I had to follow the directions quite explicitly, there was a spreadsheet involved to calculate some of the parameters that went in the MSG block parameters, and that maybe the documentation was a bit spread out on digi's website.


I will be ordering a couple more digi one IAPs this year so will be able to offer specific help then. You also need to supply more specific information about your setup for someone on this forum to be able to spot a problem and help you.



You could also use wireshark to see what traffic is coming and going from the digi one IAP so at least that way you will know what the control logix is sending to it (if anything), what the digi is sending to your modbus device (if anything), what the reply was (if anything), etc, in order to spot where the chain falls apart.
 
I had a good experience with the digi one IAP. three different Control Logix PLCs reading 6 different modbus slaves all at the same time.


I can't remember the specifics of the setup other than I had to follow the directions quite explicitly, there was a spreadsheet involved to calculate some of the parameters that went in the MSG block parameters, and that maybe the documentation was a bit spread out on digi's website.


I will be ordering a couple more digi one IAPs this year so will be able to offer specific help then. You also need to supply more specific information about your setup for someone on this forum to be able to spot a problem and help you.



You could also use wireshark to see what traffic is coming and going from the digi one IAP so at least that way you will know what the control logix is sending to it (if anything), what the digi is sending to your modbus device (if anything), what the reply was (if anything), etc, in order to spot where the chain falls apart.

You wouldnt have the digi one Config and message setup that i could look over do you?
 
see attached excel file for calculating the MSG parameters.
see attached .cfg file (renamed to .txt so the forum would accept it) which is the digi's configuration file I dug up from 2014.

this page seems to have all the documentation:
https://www.digi.com/products/netwo...erial-servers/digioneiapfamily#productsupport

I recall using this guide:
http://www.digi.com/resources/documentation/digidocs/pdfs/90000643.pdf

The PLC program MSG block for reading from holding register 125 of a modbus slave is
Configuration tab:
message type: SLC typed read
source element: N251:26 (oddly this is the address range for reading input registers according to the excel sheet?)
number of elements: 60
destination element: some tag array of INT[64]

Communication tab:
Path: ETH0, 2, 172.30.111.42(digi's IP):44819
communication method: CIP with source ID
source link 0, destination link 0, destination node 36 (octal)

the next several reads in the PLC program are to a different device. The MSG Block configuration has a different source element and number of elements according to which registers are to be read, uses the same IP/port of the digi, but has a destination node of 37 which must somehow map to the IP of the other modbus slave in the digi configuration.
 

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