# Modbus TCP Connected Device Works with Modpoll but NOT on Ignition! **URL:** \ **Category:** Ignition\ **Tags:** ignition81\ **Created:** [February 9, 2022, 3:22pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connected-device-works-with-modpoll-but-not-on-ignition/55916 "2022-02-09T15:22:49Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![John\_Reilly](https://avatars.discourse-cdn.com/v4/letter/j/85e7bf/32.png) [@John\_Reilly](https://forum.inductiveautomation.com/u/John_Reilly)\ **Post date:** [February 9, 2022, 3:22pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connected-device-works-with-modpoll-but-not-on-ignition/55916/1 "2022-02-09T15:22:49Z")
Hi, I’m having issue pulling modbus data into Ignition. Using Modpoll I am able to pull the correct data from the Modbus gateway using the following command. ```auto modpoll -t4:float -f -0 -r 16 -c 62 -l 10 192.168.1.100 ``` -t 4:float 32-bit float data type in output (holding) register table -f Slave operates on big-endian 32-bit floats -0 First reference is 0 (PDU addressing) instead 1 -r # Start reference (1-65536, 1 is default) -c # Number of values to read (1-125, 1 is default), optional for writ -l Poll rate in ms, (1000 is default) ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/6/9/69b1e24191f745b80965c159c032c1ecf7455713.png) _ **NOTE The addresses are half the Byte value given to me in the Modbus Address Table** _ MODBUS Address Table snippet shown here ![Modbus Tags Table](https://us1.discourse-cdn.com/inductiveautomation/original/3X/8/3/83df540f1fad8435c69e37fbff2106154fc84f41.png) The Modbus address offset is 4 Bytes (32 Bits) and Big Endian and in the holding register. Below is the system config info the modbus gateway was given to us. _REMOVED LINK AS NEW POSTER ONLY ALLOWED 3 IMG - Will upload in replies_ Using Ignition 8.1 I thought it would be straight forward to get the same data pulled over and followed the guides provided by Ignition [https://docs.inductiveautomation.com/display/DOC80/Connecting+to+Modbus+Device](https://docs.inductiveautomation.com/display/DOC80/Connecting+to+Modbus+Device) Below is the settings used on my Ignition Gateway in the OPC UA Device Connections. _REMOVED LINK AS NEW POSTER - Will upload in replies_ Following these ignition guides I got erronious data getting pulled through Ignition, as shown below. ![Modbus Tags Values](https://us1.discourse-cdn.com/inductiveautomation/original/3X/8/e/8e3cd9064f489ca20b8a0a68c17d66b6a42f1035.png) The tags were written like below. _REMOVED LINK AS NEW POSTER ONLY ALLOWED 3 IMG - Will upload in replies_ [Radial\_Forge]HR56 & HRF56 Even tried this forum post [https://forum.inductiveautomation.com/t/modbus-read-two-register-into-one-opc-tag/41858](https://forum.inductiveautomation.com/t/modbus-read-two-register-into-one-opc-tag/41858) _REMOVED LINK AS NEW POSTER ONLY ALLOWED 3 IMG - Will upload in replies_ I believe I must be doing something stupid or missing one vital step. If anyone is able to help me it would be greatly appreciated! Thank you, John ---
**Author:** ![John\_Reilly](https://avatars.discourse-cdn.com/v4/letter/j/85e7bf/32.png) [@John\_Reilly](https://forum.inductiveautomation.com/u/John_Reilly)\ **Post date:** [February 9, 2022, 3:25pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connected-device-works-with-modpoll-but-not-on-ignition/55916/2 "2022-02-09T15:25:38Z")
Below is the system config info the modbus gateway was given to us. ![Modbus Gateway Config](https://us1.discourse-cdn.com/inductiveautomation/original/3X/7/d/7d1865b904e53764399ebb360edae98339ee2eaa.png) Below is the settings used on my Ignition Gateway in the OPC UA Device Connections. ![Ignition - Modbus Device Connection Settings.jpeg](https://us1.discourse-cdn.com/inductiveautomation/original/3X/9/8/988579015028eeae213870fdd246454c93013f50.png) [Radial\_Forge]HR56 & HRF56 The tags were written like below. ![Modbus Tags Path](https://us1.discourse-cdn.com/inductiveautomation/original/3X/1/6/167a81164d466ab96492aed46c6abd2d18a0201e.png) ---
**Author:** ![John\_Reilly](https://avatars.discourse-cdn.com/v4/letter/j/85e7bf/32.png) [@John\_Reilly](https://forum.inductiveautomation.com/u/John_Reilly)\ **Post date:** [February 9, 2022, 3:26pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connected-device-works-with-modpoll-but-not-on-ignition/55916/3 "2022-02-09T15:26:08Z")
Even tried this forum post [Modbus read two register into one opc tag](https://forum.inductiveautomation.com/t/modbus-read-two-register-into-one-opc-tag/41858) ![Modbus Tags Path - Using dervied tag](https://us1.discourse-cdn.com/inductiveautomation/original/3X/e/7/e77cf15a2c3dfb7bb4035aedb2f1786dd1c5f36f.png) ---
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [February 9, 2022, 3:26pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connected-device-works-with-modpoll-but-not-on-ignition/55916/4 "2022-02-09T15:26:52Z")
The address table appears to suggest they are zero-based. Ignition’s driver defaults to one-based. Change that setting on your device. Your OPC item path would be `[Radial_Forge]HRF56`. You might also want to play with the swap words setting. You may also need the node number. Like `[Radial_Forge]1.HRF56`. ---
**Author:** ![John\_Reilly](https://avatars.discourse-cdn.com/v4/letter/j/85e7bf/32.png) [@John\_Reilly](https://forum.inductiveautomation.com/u/John_Reilly)\ **Post date:** [February 9, 2022, 3:28pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connected-device-works-with-modpoll-but-not-on-ignition/55916/5 "2022-02-09T15:28:35Z")
I believe in the image shared I had ticked the zero based addressing. Is this what you mean? ---
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [February 9, 2022, 3:47pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connected-device-works-with-modpoll-but-not-on-ignition/55916/6 "2022-02-09T15:47:58Z")
I’m pretty sure you need “Swap Words” **off**. ---
**Author:** ![John\_Reilly](https://avatars.discourse-cdn.com/v4/letter/j/85e7bf/32.png) [@John\_Reilly](https://forum.inductiveautomation.com/u/John_Reilly)\ **Post date:** [February 10, 2022, 5:10pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connected-device-works-with-modpoll-but-not-on-ignition/55916/7 "2022-02-10T17:10:12Z")
Hi Pturmel, I’ve tried Swap Word off and went through settings togging on/off and still go same erronious values. I see you spoke about Node number. How would I find out what node number? Is this on Modbus gateway or Ignition platform. I tried using `[Radial_Forge]1.HRF56` . and got error\_config as value. Any help would really be greatly appreciated, thanks! ---
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [February 10, 2022, 5:13pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connected-device-works-with-modpoll-but-not-on-ignition/55916/8 "2022-02-10T17:13:27Z")
I recommend you use wireshark to capture the traffic first with modpoll, then with Ignition, and share those files here. That will help narrow down the problem. ---
**Author:** ![John\_Reilly](https://avatars.discourse-cdn.com/v4/letter/j/85e7bf/32.png) [@John\_Reilly](https://forum.inductiveautomation.com/u/John_Reilly)\ **Post date:** [July 26, 2022, 10:41am UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connected-device-works-with-modpoll-but-not-on-ignition/55916/9 "2022-07-26T10:41:06Z")
I have got it working with the Reverse Word Order in Iginition gateway set to **FALSE** and halfing the modbus values given to me in the pdf as it using 2 bytes. It was a sort of infinite monkeys and typewritters for finding the solution 🤣 hopefully this helps someone else. See below images for details of the changes, the example tag is the same as origional question but showing it works. ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/9/e/9ecdd90d03c9fdeb269fe3507cd62299f6316ce6.png) ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/4/a/4a6fcfc3db44b4a01698bc716269b864c05bf4c3.png)