# \#modbus **URL:** https://forum.inductiveautomation.com/tag/modbus/74.md [Latest](https://forum.inductiveautomation.com/latest.md) · [Categories](https://forum.inductiveautomation.com/categories.md) · [Tags](https://forum.inductiveautomation.com/tags.md) --- ## [Modbus TCP failing on more than 1 slave device read](https://forum.inductiveautomation.com/t/modbus-tcp-failing-on-more-than-1-slave-device-read/117129)
**Author:** [@william.agbo](https://forum.inductiveautomation.com/u/william.agbo)\ **Replies:** 17\ **Last updated:** [September 22, 2026, 9:32pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-failing-on-more-than-1-slave-device-read/117129 "2026-09-22T21:32:28Z")
I have a USR DR302 rs485 to tcp gateway(converter). I connect it to ignition using the Modbus TCP driver but noticed that when I try to request tag data for more than two slaves it starts giving me bad tag value and tim… --- ## [\[Tool Share / Feedback Wanted\] Two Modbus debugging tools: MBSim slave simulator + ModbusGateway TCP/RTU software gateway](https://forum.inductiveautomation.com/t/tool-share-feedback-wanted-two-modbus-debugging-tools-mbsim-slave-simulator-modbusgateway-tcp-rtu-software-gateway/115664)
**Author:** [@louis.androidor](https://forum.inductiveautomation.com/u/louis.androidor)\ **Replies:** 2\ **Last updated:** [June 10, 2026, 7:35am UTC](https://forum.inductiveautomation.com/t/tool-share-feedback-wanted-two-modbus-debugging-tools-mbsim-slave-simulator-modbusgateway-tcp-rtu-software-gateway/115664 "2026-06-10T07:35:22Z")
Hi everyone, I recently organized and released two Modbus debugging tools that I maintain personally, and I would like to share them here for testing and feedback. The first one is MBSim, a Modbus RTU/TCP slave simulat… --- ## [uSwitch CS Modbus TCP Weirdness](https://forum.inductiveautomation.com/t/uswitch-cs-modbus-tcp-weirdness/115892)
**Author:** [@dion.botha](https://forum.inductiveautomation.com/u/dion.botha)\ **Replies:** 1\ **Last updated:** [June 8, 2026, 2:51pm UTC](https://forum.inductiveautomation.com/t/uswitch-cs-modbus-tcp-weirdness/115892 "2026-06-08T14:51:18Z")
Hello, I have this device connected to Ignition using the Modbus TCP driver with all default settings. Among other things, it has 2 general purpose input points and 2 relay outputs. If I try to address, the first relay … --- ## [Modbus RTU over TCP: Single slave timeout causes driver to drop entire TCP connection (FailureType==DISCONNECTED)](https://forum.inductiveautomation.com/t/modbus-rtu-over-tcp-single-slave-timeout-causes-driver-to-drop-entire-tcp-connection-failuretype-disconnected/115707)
**Author:** [@piperra](https://forum.inductiveautomation.com/u/piperra)\ **Replies:** 17\ **Last updated:** [May 27, 2026, 12:45pm UTC](https://forum.inductiveautomation.com/t/modbus-rtu-over-tcp-single-slave-timeout-causes-driver-to-drop-entire-tcp-connection-failuretype-disconnected/115707 "2026-05-27T12:45:27Z")
Hi everyone, I'm running into a frustrating issue with the Modbus driver in Ignition 8.3, and I'm hoping someone can point me in the right direction. The Architecture: Gateway: Ignition 8.3 Hardware: 6 Modbus RTU… --- ## [Modbus RTU request with a custom write command](https://forum.inductiveautomation.com/t/modbus-rtu-request-with-a-custom-write-command/115591)
**Author:** [@amurillo](https://forum.inductiveautomation.com/u/amurillo)\ **Replies:** 1\ **Last updated:** [May 19, 2026, 12:02pm UTC](https://forum.inductiveautomation.com/t/modbus-rtu-request-with-a-custom-write-command/115591 "2026-05-19T12:02:36Z")
Hello, I am working with an inverter that only writes with a personalized command, soo I can't use system.opc.writeValues(). I'm trying to close the modbus device I have in the gateway and open the port with system.seria… --- ## [Modbus device always disconnected](https://forum.inductiveautomation.com/t/modbus-device-always-disconnected/115137)
**Author:** [@GeraldB](https://forum.inductiveautomation.com/u/GeraldB)\ **Replies:** 3\ **Last updated:** [April 27, 2026, 2:30pm UTC](https://forum.inductiveautomation.com/t/modbus-device-always-disconnected/115137 "2026-04-27T14:30:34Z")
Hello, I have connected 43 modbus devices to a Ignition server. 25 are Analog-Digital converters and the other 18 are energy meters (Siemens PAC 3200 and Siemens PAC 2200) All Energy meters are in the same network segm… --- ## [Modbus Float Polling](https://forum.inductiveautomation.com/t/modbus-float-polling/114495)
**Author:** [@Ryan\_Shaw](https://forum.inductiveautomation.com/u/Ryan_Shaw)\ **Replies:** 8\ **Last updated:** [March 15, 2026, 9:43pm UTC](https://forum.inductiveautomation.com/t/modbus-float-polling/114495 "2026-03-15T21:43:58Z")
Hi all. I am studying how Modbus TCP protocol works in Ignition using a Codesys Control Win V3 SoftPLC as a PLC emulator. In the PLC, I created a union for my float types as this was the only way I found I was able to … --- ## [Modbus CLI utility for client and server testing](https://forum.inductiveautomation.com/t/modbus-cli-utility-for-client-and-server-testing/111882)
**Author:** [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Replies:** 1\ **Last updated:** [February 16, 2026, 6:25pm UTC](https://forum.inductiveautomation.com/t/modbus-cli-utility-for-client-and-server-testing/111882 "2026-02-16T18:25:50Z")
I started working on a little Modbus CLI utility: GitHub - kevinherron/modbus-cli: Native CLI utility for reading, writing, and scanning Modbus TCP Ripped from the README, some quick examples: Quick Examples Start a te… --- ## [Modbus Tags "Bad\_NotConnected" When polling more than one device](https://forum.inductiveautomation.com/t/modbus-tags-bad-notconnected-when-polling-more-than-one-device/92865)
**Author:** [@Ali\_R](https://forum.inductiveautomation.com/u/Ali_R)\ **Replies:** 23\ **Last updated:** [January 22, 2026, 7:18pm UTC](https://forum.inductiveautomation.com/t/modbus-tags-bad-notconnected-when-polling-more-than-one-device/92865 "2026-01-22T19:18:26Z")
Hi everyone, I am new to modbus systems now I have 4 RTU over RS485 devices ( Address 1: VFD, 2 and 3: Schneider PM2220 Powermeters and 4: Delta PLC). I have added their modbus addresses through Ignition Address mapping… --- ## [Modbus Data Reading and conversion](https://forum.inductiveautomation.com/t/modbus-data-reading-and-conversion/113052)
**Author:** [@Adam\_Feigum](https://forum.inductiveautomation.com/u/Adam_Feigum)\ **Replies:** 2\ **Last updated:** [January 2, 2026, 4:56pm UTC](https://forum.inductiveautomation.com/t/modbus-data-reading-and-conversion/113052 "2026-01-02T16:56:46Z")
I’m trying to collect data off of some modbus devices i can see the data in Modscan and the correct Holding Registers but can not seem to get the mapping correct in ignition what am i doing wrong here I also have tri… --- ## [Troubleshooting Ignition to M340 PLC over Modbus TCP](https://forum.inductiveautomation.com/t/troubleshooting-ignition-to-m340-plc-over-modbus-tcp/112578)
**Author:** [@ericksone](https://forum.inductiveautomation.com/u/ericksone)\ **Replies:** 5\ **Last updated:** [December 3, 2025, 3:02pm UTC](https://forum.inductiveautomation.com/t/troubleshooting-ignition-to-m340-plc-over-modbus-tcp/112578 "2025-12-03T15:02:21Z")
I have an m340 PLC using a P34-1000 card (ver 3.5) and a NOE 0100.2 (ver 3.5), ignition modbus driver is 7.1.35. This is behind a tailscale router with the ignition server on the tailscale network as well. I am able to… --- ## [Modbus cool tool](https://forum.inductiveautomation.com/t/modbus-cool-tool/112325)
**Author:** [@Arnaud\_Declerck](https://forum.inductiveautomation.com/u/Arnaud_Declerck)\ **Replies:** 2\ **Last updated:** [November 21, 2025, 10:06pm UTC](https://forum.inductiveautomation.com/t/modbus-cool-tool/112325 "2025-11-21T22:06:16Z")
Hi Everyone, Just want to share a cool tool that i just found for the Modbus freak :wink: Regards Arnaud --- ## [Creating tag groups with the openapi endpoints in the gateway?](https://forum.inductiveautomation.com/t/creating-tag-groups-with-the-openapi-endpoints-in-the-gateway/111633)
**Author:** [@epaulson](https://forum.inductiveautomation.com/u/epaulson)\ **Replies:** 10\ **Last updated:** [November 6, 2025, 4:22pm UTC](https://forum.inductiveautomation.com/t/creating-tag-groups-with-the-openapi-endpoints-in-the-gateway/111633 "2025-11-06T16:22:28Z")
I am brand-new to Ignition (I set up my first gateway last week) so I apologize if this is a dumb question, but is it possible to create and assign tag groups through the API the gateway exposes (which I think is new in … --- ## [Ignition Modbus Master/Slave](https://forum.inductiveautomation.com/t/ignition-modbus-master-slave/111474)
**Author:** [@derek.stoddard](https://forum.inductiveautomation.com/u/derek.stoddard)\ **Replies:** 5\ **Last updated:** [October 15, 2025, 7:44pm UTC](https://forum.inductiveautomation.com/t/ignition-modbus-master-slave/111474 "2025-10-15T19:44:06Z")
I have been unable to find a definitive answer in the documentation–am I correct in saying Ignition must act as the master in a Modbus configuration? --- ## [Modbus tags have bad quality, not sure what to check further](https://forum.inductiveautomation.com/t/modbus-tags-have-bad-quality-not-sure-what-to-check-further/111432)
**Author:** [@hoangduong.vu83](https://forum.inductiveautomation.com/u/hoangduong.vu83)\ **Replies:** 16\ **Last updated:** [October 15, 2025, 7:34am UTC](https://forum.inductiveautomation.com/t/modbus-tags-have-bad-quality-not-sure-what-to-check-further/111432 "2025-10-15T07:34:26Z")
Hi all, this is my first time setting up Modbus with Ignition. The device here is an Air Compressor with Modbus RTU. I used gateway device USR-TCP232-304 as the bridge to TCP and connected to Ignition successfully. I hav… --- ## [Writing to Red Lion PLC via Modbus](https://forum.inductiveautomation.com/t/writing-to-red-lion-plc-via-modbus/110849)
**Author:** [@derek.stoddard](https://forum.inductiveautomation.com/u/derek.stoddard)\ **Replies:** 25\ **Last updated:** [October 1, 2025, 3:24pm UTC](https://forum.inductiveautomation.com/t/writing-to-red-lion-plc-via-modbus/110849 "2025-10-01T15:24:26Z")
Hello, I’m trying to write to a Red Lion EtherTRAK E2 via Modbus in Ignition 8.1. The OPC Item Path starts with HR and I am able to read the tag but not write to it. Anyone have any experience with this? --- ## [Best practices for working with Modbus/TCP](https://forum.inductiveautomation.com/t/best-practices-for-working-with-modbus-tcp/111030)
**Author:** [@ivan.macias](https://forum.inductiveautomation.com/u/ivan.macias)\ **Replies:** 5\ **Last updated:** [September 29, 2025, 3:24pm UTC](https://forum.inductiveautomation.com/t/best-practices-for-working-with-modbus-tcp/111030 "2025-09-29T15:24:57Z")
I didn’t want to necro the threads where I saw this advice given, but I was wanting to get a clearer answer on this. The inductive automation training seems to direct you to use the address mapping feature in the Gateway… --- ## [Bulk Modbus Tags Adding](https://forum.inductiveautomation.com/t/bulk-modbus-tags-adding/110475)
**Author:** [@Allen\_Thomas](https://forum.inductiveautomation.com/u/Allen_Thomas)\ **Replies:** 1\ **Last updated:** [September 9, 2025, 12:50pm UTC](https://forum.inductiveautomation.com/t/bulk-modbus-tags-adding/110475 "2025-09-09T12:50:10Z")
I’m working with MODBUS TCP to communicate with different PLC that contains approximately 30,000 registers. I need to bring these registers into Ignition as tags, but I’m running into a couple of challenges: The regis… --- ## [Modbus TCP - A slave in one physical chain acting as a master in another](https://forum.inductiveautomation.com/t/modbus-tcp-a-slave-in-one-physical-chain-acting-as-a-master-in-another/109558)
**Author:** [@Melby\_Miraval](https://forum.inductiveautomation.com/u/Melby_Miraval)\ **Replies:** 2\ **Last updated:** [August 9, 2025, 9:31pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-a-slave-in-one-physical-chain-acting-as-a-master-in-another/109558 "2025-08-09T21:31:52Z")
I have 3 Modbus RTU devices connecting to the Ignition SCADA via a RTU to TCP Gateway. I am using Modbus TCP. I know I can reach the tags from these devices using \[Gateway\]\[slaveID\].tagpath One of those 3 RTU devices … --- ## [Ignition - SENTRON PAC3200 - connection via MODBUS TCP](https://forum.inductiveautomation.com/t/ignition-sentron-pac3200-connection-via-modbus-tcp/108040)
**Author:** [@rafal.samoraj](https://forum.inductiveautomation.com/u/rafal.samoraj)\ **Replies:** 2\ **Last updated:** [July 30, 2025, 2:30pm UTC](https://forum.inductiveautomation.com/t/ignition-sentron-pac3200-connection-via-modbus-tcp/108040 "2025-07-30T14:30:18Z")
Hello, I'm trying to connect to a SIEMENS SENTRON PAC3200 power monitoring device via MODBUS TCP. There is a connection between the Ignition gateway and the SENTRON device, but I can't read any registers. I suppose th… --- ## [Modbus Communication Issue Between Ignition and jlibmodbus Code](https://forum.inductiveautomation.com/t/modbus-communication-issue-between-ignition-and-jlibmodbus-code/108846)
**Author:** [@Spencer\_Lommel1](https://forum.inductiveautomation.com/u/Spencer_Lommel1)\ **Replies:** 2\ **Last updated:** [July 23, 2025, 6:55pm UTC](https://forum.inductiveautomation.com/t/modbus-communication-issue-between-ignition-and-jlibmodbus-code/108846 "2025-07-23T18:55:29Z")
What I'm attempting to do I am working on a custom Java application that implements Modbus using this jlibmodbus library My Modbus Client Code I was able to get a simple ModbusTCP client going with this example code tha… --- ## [Problem connecting Ignition to Modbus TCP slave simulator (status: Connected, but no data)](https://forum.inductiveautomation.com/t/problem-connecting-ignition-to-modbus-tcp-slave-simulator-status-connected-but-no-data/108498)
**Author:** [@wera.rum](https://forum.inductiveautomation.com/u/wera.rum)\ **Replies:** 12\ **Last updated:** [July 18, 2025, 1:50pm UTC](https://forum.inductiveautomation.com/t/problem-connecting-ignition-to-modbus-tcp-slave-simulator-status-connected-but-no-data/108498 "2025-07-18T13:50:59Z")
Hi everyone, I’m trying to connect Ignition to a Modbus TCP slave simulator, but I can’t get it to work properly. :wrench: What I’m doing: Using Ignition (non-commercial version) Tried two simulators as Modbus slaves… --- ## [Modbus TCP connection to a Eurotherm nanodac](https://forum.inductiveautomation.com/t/modbus-tcp-connection-to-a-eurotherm-nanodac/104508)
**Author:** [@m.benlarbi](https://forum.inductiveautomation.com/u/m.benlarbi)\ **Replies:** 9\ **Last updated:** [June 20, 2025, 3:24pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connection-to-a-eurotherm-nanodac/104508 "2025-06-20T15:24:24Z")
Hello Everyone, Has anyone had experience accessing a Nanodac parameter via Modbus TCP in Ignition? I’ve added the device ,the statut of the device is connected, but when I attempt to read a parameter, I get a timeout … --- ## [Help diagnosing MODBUS TCP timeout issues](https://forum.inductiveautomation.com/t/help-diagnosing-modbus-tcp-timeout-issues/106792)
**Author:** [@L\_F](https://forum.inductiveautomation.com/u/L_F)\ **Replies:** 2\ **Last updated:** [May 28, 2025, 9:14pm UTC](https://forum.inductiveautomation.com/t/help-diagnosing-modbus-tcp-timeout-issues/106792 "2025-05-28T21:14:40Z")
I am trying to connect to a chiller/circulator using MODBUD over TCP. I have created the connection in the OPC UA section of my server, and I see it appear in my Vision Designer. I think I am using the write OPC path, bu… --- ## [RACO Catalyst Modbus Addressing questions](https://forum.inductiveautomation.com/t/raco-catalyst-modbus-addressing-questions/106009)
**Author:** [@jordan.richardson](https://forum.inductiveautomation.com/u/jordan.richardson)\ **Replies:** 5\ **Last updated:** [May 8, 2025, 2:12pm UTC](https://forum.inductiveautomation.com/t/raco-catalyst-modbus-addressing-questions/106009 "2025-05-08T14:12:29Z")
Before I get too far down a rabbit hole I'd like to see if it's even possible to communicate to a RACO C10-020-1450E. The support page for the connection guide can be found here. The main point of concern from that docum… --- ## [Automation Direct GS4 VFD Modbus TCP](https://forum.inductiveautomation.com/t/automation-direct-gs4-vfd-modbus-tcp/105895)
**Author:** [@edward.schweizer](https://forum.inductiveautomation.com/u/edward.schweizer)\ **Replies:** 3\ **Last updated:** [May 5, 2025, 9:11pm UTC](https://forum.inductiveautomation.com/t/automation-direct-gs4-vfd-modbus-tcp/105895 "2025-05-05T21:11:35Z")
Didn't seem to have luck with this direct device when searching on the forums so forgive me if there is a post already. I'm having trouble getting valid Modbus TCP data from an Automation Direct GS4 VFD. I am able to u… --- ## [Check Out This Handy Modbus TCP Simulator for SCADA Development 🌟](https://forum.inductiveautomation.com/t/check-out-this-handy-modbus-tcp-simulator-for-scada-development/105333)
**Author:** [@a.alghannam](https://forum.inductiveautomation.com/u/a.alghannam)\ **Replies:** 13\ **Last updated:** [April 21, 2025, 8:16pm UTC](https://forum.inductiveautomation.com/t/check-out-this-handy-modbus-tcp-simulator-for-scada-development/105333 "2025-04-21T20:16:24Z")
Testing SCADA systems without real hardware can be a pain, but this generic Modbus TCP simulator I built makes it a breeze. It’s a simple yet powerful tool that mimics industrial devices, letting you develop and test … --- ## [UDT Tags Not Updating Consistently for Modbus TCP Devices](https://forum.inductiveautomation.com/t/udt-tags-not-updating-consistently-for-modbus-tcp-devices/104994)
**Author:** [@AP25](https://forum.inductiveautomation.com/u/AP25)\ **Replies:** 8\ **Last updated:** [April 14, 2025, 3:37pm UTC](https://forum.inductiveautomation.com/t/udt-tags-not-updating-consistently-for-modbus-tcp-devices/104994 "2025-04-14T15:37:10Z")
Hi all, I'm facing an issue with a Modbus TCP device connection in the Ignition gateway. Here are the details: 1. Connection Settings: Timeout: 10000ms Radix: 10 2. Tag Configuration: UDTs are created using the mul… --- ## [Could someone help integrate energy meter ION 7400 to Ignition using Modbus TCP](https://forum.inductiveautomation.com/t/could-someone-help-integrate-energy-meter-ion-7400-to-ignition-using-modbus-tcp/104415)
**Author:** [@ALLEN\_LAPA](https://forum.inductiveautomation.com/u/ALLEN_LAPA)\ **Replies:** 2\ **Last updated:** [March 30, 2025, 2:20am UTC](https://forum.inductiveautomation.com/t/could-someone-help-integrate-energy-meter-ion-7400-to-ignition-using-modbus-tcp/104415 "2025-03-30T02:20:10Z")
Hi everyone..! We have energy meter ION 7400. We have a mapping adreses, e.g. the frecuency is 3110 and use 2 register. I see on modbus pool on 2 register 43110 and 43111 I dont know how to integrate. Could help us? … --- ## [Haier Biomedical Freezer](https://forum.inductiveautomation.com/t/haier-biomedical-freezer/103882)
**Author:** [@jakned](https://forum.inductiveautomation.com/u/jakned)\ **Replies:** 5\ **Last updated:** [March 19, 2025, 1:55pm UTC](https://forum.inductiveautomation.com/t/haier-biomedical-freezer/103882 "2025-03-19T13:55:29Z")
Hi, does anyone have a experience with connecting Haier Biomedical freezer using their RS485 interface running Modbus RTU (thats what they claim)? I use a Modbus TCP to RTU converter that i tested with other RS485 Modbu… [Next page](https://forum.inductiveautomation.com/tag/modbus/74.md?match_all_tags=true&page=1&tags%5B%5D=modbus)