# Modbus TCP connection to a Eurotherm nanodac **URL:** \ **Category:** Ignition\ **Tags:** modbus\ **Created:** [April 1, 2025, 12:04pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connection-to-a-eurotherm-nanodac/104508 "2025-04-01T12:04:14Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![m.benlarbi](https://avatars.discourse-cdn.com/v4/letter/m/65b543/32.png) [@m.benlarbi](https://forum.inductiveautomation.com/u/m.benlarbi)\ **Post date:** [April 1, 2025, 12:04pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connection-to-a-eurotherm-nanodac/104508/1 "2025-04-01T12:04:14Z")
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 error. Here’s the error message I’m receiving: ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/c/9/c9bf0919a3d85b2acb325223a2fec6c28a607776.png) I followed the Modbus addressing recommendations from the Nanodac datasheet, as shown here: ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/1/1/11f6d1417017f88e672db9f13749457f15f1690c.png) Let me know if you need more information,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:** [April 1, 2025, 12:10pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connection-to-a-eurotherm-nanodac/104508/2 "2025-04-01T12:10:43Z")
- Does the documentation indicate what unit number to use? Ignition defaults to unit #0, but many devices need something else. (Commonly, unit #1.) - That snippet of the documentation suggests that the device uses zero-based addressing. Check the advanced settings of your device in Ignition. Perhaps you can share the complete doc? Or a link to it? ---
**Author:** ![m.benlarbi](https://avatars.discourse-cdn.com/v4/letter/m/65b543/32.png) [@m.benlarbi](https://forum.inductiveautomation.com/u/m.benlarbi)\ **Post date:** [April 1, 2025, 12:19pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connection-to-a-eurotherm-nanodac/104508/3 "2025-04-01T12:19:43Z")
This is the link of the nanodac, > **[HA030554\_8-nanodac-user-manual-1.pdf](https://www.surecontrols.com/wp-content/uploads/2014/08/HA030554_8-nanodac-user-manual-1.pdf)** > > 11.03 MB ---
**Author:** ![m.benlarbi](https://avatars.discourse-cdn.com/v4/letter/m/65b543/32.png) [@m.benlarbi](https://forum.inductiveautomation.com/u/m.benlarbi)\ **Post date:** [April 1, 2025, 12:22pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connection-to-a-eurotherm-nanodac/104508/4 "2025-04-01T12:22:49Z")
- Does the documentation indicate what unit number to use? Ignition defaults to unit #0, but many devices need something else. **Its not specified on the datasheet** - That snippet of the documentation suggests that the device uses zero-based addressing. Check the advanced settings of your device in Ignition, **i played tried to add and substitude 1 to check but same issue** ---
**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:** [April 1, 2025, 12:36pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connection-to-a-eurotherm-nanodac/104508/5 "2025-04-01T12:36:20Z")
Try using unit #1, and definitely use zero-based addressing. (Changing the latter would not get rid of the error caused by the wrong unit number.) Try this OPC Item Path in a test tag: ```python [yourDevice]1.HR791 ``` That should be `AdvancedLoop.Main.MasterPV` with one implied decimal place. The floating point address for that is 0x8000 + 2 \* 791 =\> ```python [yourDevice]1.HRF34350 ``` ---
**Author:** ![m.benlarbi](https://avatars.discourse-cdn.com/v4/letter/m/65b543/32.png) [@m.benlarbi](https://forum.inductiveautomation.com/u/m.benlarbi)\ **Post date:** [April 1, 2025, 12:58pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connection-to-a-eurotherm-nanodac/104508/6 "2025-04-01T12:58:05Z")
> [@pturmel](#): > > `1.HRF34350` ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/e/1/e1e5cf1769a230141b71b081767b7ea32b5ef091.png) I tried it ,it seems to give the same result ---
**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:** [April 1, 2025, 1:03pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connection-to-a-eurotherm-nanodac/104508/7 "2025-04-01T13:03:11Z")
Why did you name that tag "Connected" ? But anyways, you need to: - Scour the user manual for examples that might show what unit # that device actually uses, and - Use wireshark or similar to see if **any** communication to that device is occurring--perhaps a firewall is interfering. ---
**Author:** ![m.benlarbi](https://avatars.discourse-cdn.com/v4/letter/m/65b543/32.png) [@m.benlarbi](https://forum.inductiveautomation.com/u/m.benlarbi)\ **Post date:** [April 1, 2025, 1:36pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connection-to-a-eurotherm-nanodac/104508/8 "2025-04-01T13:36:36Z")
🤣,i used the opc browser to add the tag connected (the modbus device status),i just keep it and work with it. Thanks ,i will check that and let you know ---
**Author:** ![gabriel.connor](https://avatars.discourse-cdn.com/v4/letter/g/43a26b/32.png) [@gabriel.connor](https://forum.inductiveautomation.com/u/gabriel.connor)\ **Post date:** [May 27, 2025, 4:10pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connection-to-a-eurotherm-nanodac/104508/9 "2025-05-27T16:10:25Z")
Hello, Was there a resolution to the issue? I am having the same issue on a nanodac controller; no communication possible via Modbus. ---
**Author:** ![m.benlarbi](https://avatars.discourse-cdn.com/v4/letter/m/65b543/32.png) [@m.benlarbi](https://forum.inductiveautomation.com/u/m.benlarbi)\ **Post date:** [June 20, 2025, 3:24pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connection-to-a-eurotherm-nanodac/104508/10 "2025-06-20T15:24:24Z")
Hello Gabriel No,Finally we just split the 4-20ma pressure signal and install a new plc to be able to read it Let me know if you find a way to deal with it.Thanks