Automation Direct DL240 Mapping Issue?


So, I am connected to an Automation Direct DL240 processor that runs a small process at one of our plants and I am having issues with the bit addresses. I have tried both manual mapping and using the DL240 map template from the Inductive website. I can access all of the holding registers with no issues, but when I map the coils, inputs and outputs the values in Ignition do not match the live values in the PLC. As can be seen below, Ignition shows coils 4, 5 and 7 on, but the program shows coils 4 and 6 as on… Anyone seen this before? Ideas?

Can you get a Wireshark capture?

Please explain, Kevin!

Wireshark is at tool for monitoring and capturing network traffic. If you’re not familiar with it then never mind my request. Give support a call and they can help you figure out if the response from the device is indeed indicating the values you’re seeing or if there’s some kind of mismatch somewhere.


I understand Wireshark, just not it’s application to Modbus mapping. The weird thing is that the holding registers map fine, the bits are the problem - coils, inputs and outputs. I will advise if we figure out the issue, we will be working on this tomorrow! Thanks for the advice!

I want to see if the PLC is reporting the status of those coils incorrectly or if there’s a problem in Ignition that needs looking into.


On initial observation, it looks like the PLC is not mapping to Modbus right… Using ModScan to diagnose the issue, but the whole octal to decimal conversion with offsets is a trick to map in real time. More to come tomorrow!

What are you using for your OPC Item Path for CR0 (for example)? According to the information I have, it should be [DeviceName]c3073

The next few registers should be:
C1 - [DeviceName]c3074
C2 - [DeviceName]c3075

Note: C8, and C9 do not exist in the DL240, it’s octal based addressing.
C10 - [DeviceName]c3081
C11 - [DeviceName]c3082

Also something to check, but I’m guessing you’ve got set properly already, is the Reverse Word Order option in the device settings in the Gateway webpage. This needed to be checked (turned on) for me to talk to a DL260 I have here.

Edit: The addresses I gave above are assuming that the One-based Addressing option in the device settings in the Gateway webpage has been left as the default true option.


Thanks for the input, which helped me fix the issue, though oddly enough the mapping template still doesn’t appear to work as advertised. There were two issues with the driver configuration - one was the reverse word option, which was off, the other was the start at 1 flag, which was on. Flipping those allowed me to directly address the registers after doing the octal to decimal conversion and adding the offset (if required). The mapping I set up based on the DL240 template from Inductive appeared to match the correct conversion - but the mapped coil values didn’t match the manually configured values or the live data from the PLC. Oh well, project is done and that is our only Automation Direct PLC! Thanks for the help!


I looked at the mapping file for the DL240, and it looks like they picked the wrong address to start the coil range at. That’s probably why you are having issues with it.

Glad you got it figured out!