Micro 850 to Inductive Automation Ignition via Modbus TCP

jkelleyus

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Oct 2012
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Westfield, Indiana
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All,

I know this type of question has been asked (and sometimes answered) ad infinitum but after looking I'm still stuck and could use some help.

We have several Micro 850's here and need to log a few tags via Ignition Scada. I've mapped the Modbus addresses and can access what I need on most Micro 850-'s but one is being difficult. It's also talking Modbus serial to an AB HMI.

Using Ignition (or alternatively a simple client like 'Simply Modbus') yields a 'tag does not exist' Modbus error. The issue has been reviewed by RS Tech support (the assistance was not exactly enthusiastic) and Inductive...no one has been able to figure this out.

Any pointers or help from the community would be greatly, greatly appreciated!

Thanks,

John
 
What is the exact Modbus data table address you are trying to read ?

What is the exact exception code shown by the Modbus emulator (or that you can see by intercepting the traffic with Wireshark) ? Not "Tag does not exist", but rather "Modbus Exception # X"

Can you read any of the Modbus memory map elements ?

The most common issue is when the Modbus client is trying to read a block that's too large for the defined data table in the server.
 
Thank you for the reply, Ken! After reading your posts all these years I can't tell you how fortunate I feel to have your response!!

I'm including a couple of screen shots that may help explain my setup more efficiently than I could in writing. On the 'Simply Modbus' settings on read I've tried nearly everything I can think of.....to no avail.

Any help is really appreciated!

John
 
All,

We have several Micro 850's here and need to log a few tags via Ignition Scada.

Any pointers or help from the community would be greatly, greatly appreciated!

Thanks,

John

I need to ask this question first, are all the Micro850's and Ignition on the same "Network"?

If they are - this would be fairly easy and would be very cost efficient.

Add an MQTT Gateway($390.00) to this network such as the Maple System G01-Gateway, Import all of the "TAGS" from every Micro850 into the G01.

Publish all these "Tags" to Ignition. If you will use "Cirrus Link" MQTT module for Ignition and the "Sparkplug B" protocol, this will work flawlessly!

I think the "Cirrus Link" MQTT Module is about $1200.00, but I'm not for sure - you should contact them about the price.
 
Hi John,

The JPG attachments didn't come through (at least from my view). Try saving as PNG, check to be sure you can open them, then try an Attach Files again.
 
Thanks Ken and others. I've retried uploading the two pics as PNG's.

To answer another question, the networks are the same and I can ping the processor from the server and any other device on our automation network!

We have another Micro850 here that Modbus-Ignition communicates with well. Why this one is being difficult is a mystery to me!

Thank you again for any and all help or advice!

John
 
Phooey, nothing in those images either. Try PNG, or clip them some other way, or describe them in detail.

Modbus isn't too complicated, so this should be solvable.

I don't think that Modbus RTU and Modbus/TCP are mutually exclusive on the Micro 850. Do the other working Micro 850 installations also use both serial Modbus RTU and Ethernet Modbus/TCP at the same time ?

A nice tool for troubleshooting things like this is called TCPING. It uses a simple command-line interface like the ordinary Command-line PING, but instead of ICMP it establishes a TCP connection using the specified Port number.

If you can TCPING a Micro 850 on Port 503, then you know it's running the Modbus/TCP server.
 
Have you considered trying connecting the troublesome Micro850 to Ignition as a EtherNet/IP device?

I could vouch that Modbus/TCP and EtherNet/IP data could happily coexist on any given Ethernet network/subnet.

Maybe the HMI RTU connection does indeed interfere with 'stacking' the TCP packet.
 
Last edited:
Good afternoon,

I have tried via the TCP/Ip driver but had no luck. Ignition will connect but there is no tag browse (expected) and manually entering a address in Ignition still results in a bad tag.

I'm not at all a fan of these Micro's and had considered yanking this one and putting in a ML 1400. Rockwell should not have made this so difficult.

Any other help or suggestions would be very much appreciated!

Thanks,

John
 
A couple of years ago Inductive Automation was promising a Micro800 Ethernet driver with the release of Ignition 8.0; didn't happen...:D.

I did connect Micro800s to Ignition Gateways without using Modbus TCP, however, after some investigating, we were using Kepware's Micro800 Ethernet driver where Kepware was the OPC server.

I guess, since there is an available, native Ignition Modbus TCP driver for connecting to Micro800 CPUs there really isn't any incentive for developing of another Ethernet based driver...Too bad...Modbus just turned forty...Some 'modern' perspective, huh?...:D
 
Interesting that you could get Kepware to work. I tried the demo (we run a Kepware server for BacNet currently) using AB Micro 800 driver.

While it doesn't generate any errors in Kepware, the data (bools) is not being read correctly. Do you remember how you did the addressing in Kepware on an input or other global address?

Sad AB didn't take this further.

Thank you again,

John
 
Last edited:
In looking that the pics, Simply Modbus is trying to read holding registers (function code 3) but the image of the mapping is showing coils which would use a function code 1 to be read.
 
It's been a while...And I didn't keep copies of the Kepware configurations... Generally, I try to avoid integrating bottom tier platforms within SCADA architectures...Micro800 is a stand-alone system .

Try following Kepware documentation; their Tech Support is excellent.

Micro800 is a prime example for: " You get what you pay for."...:D

https://www.kepware.com/getattachme...8e/allen-bradley-micro800-ethernet-manual.pdf
 

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