# Modbust TCP Issue **URL:** \ **Category:** Ignition\ **Tags:** perspective\ **Created:** [February 27, 2025, 9:23pm UTC](https://forum.inductiveautomation.com/t/modbust-tcp-issue/103009 "2025-02-27T21:23:12Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![tebright1](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/tebright1/32/87405_2.png) [@tebright1](https://forum.inductiveautomation.com/u/tebright1)\ **Post date:** [February 27, 2025, 9:23pm UTC](https://forum.inductiveautomation.com/t/modbust-tcp-issue/103009/1 "2025-02-27T21:23:12Z")
Having an issue where I cannot get every data point from a RedLion DSP to read at once. I have 4 blocks setup to account for 4 different types of data points. I am finding that I can only get half the values to come in. They read fine on my OPC Client. Is there something setup-wise I need to correct? _Floats set to 500ms polled. Others at default._ ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/8/3/8364be4b98001e78f09acb7996050a5cbaf2e425.png) _Change polling on an INT16 to 500ms._ ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/d/e/de37b68f6c9bf35648e4734bccfc4a39c7d8c9bd.png) _Can read all values on OPC Quick Client._ ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/7/6/76efa1f99a2b38c7e4eda376df4d8c027cf3e3e3.png) _ModbusTCP Addresses setup._ ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/3/d/3db5b909e431e3b9d8267c77105b691cd5c69304.png) ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [February 27, 2025, 9:24pm UTC](https://forum.inductiveautomation.com/t/modbust-tcp-issue/103009/2 "2025-02-27T21:24:53Z")
Try turning off the "Span Gaps" setting on the Modbus driver. ---
**Author:** ![tebright1](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/tebright1/32/87405_2.png) [@tebright1](https://forum.inductiveautomation.com/u/tebright1)\ **Post date:** [February 27, 2025, 9:31pm UTC](https://forum.inductiveautomation.com/t/modbust-tcp-issue/103009/3 "2025-02-27T21:31:45Z")
I think that fixed it! My hero! ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/1/f/1f008dc0fade64c254907cdedc3a629f1fde8fb2.png) ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [February 27, 2025, 9:32pm UTC](https://forum.inductiveautomation.com/t/modbust-tcp-issue/103009/4 "2025-02-27T21:32:14Z")
Great. Unfortunately that means RedLion has contributed yet another broken Modbus implementation to the world. ---
**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 27, 2025, 9:41pm UTC](https://forum.inductiveautomation.com/t/modbust-tcp-issue/103009/5 "2025-02-27T21:41:20Z")
> [@Kevin.Herron](#): > > broken Modbus implementation That might be a bit harsh. The lame Modbus spec permits implementers to report an error for any data address they don't want to support. In place of _broken_, I would use **lame** , **stupid** , **brain-dead** , or **lobotomized**. Or even **[expletive]** or **[expletive]** or **[expletive]-upped**. 😇 ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [February 27, 2025, 9:49pm UTC](https://forum.inductiveautomation.com/t/modbust-tcp-issue/103009/6 "2025-02-27T21:49:05Z")
The way I read this was that there's no error, but rather reading too many registers or reading across a certain boundary changes the value returned for the same registers on one end or the other. ---
**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 27, 2025, 9:53pm UTC](https://forum.inductiveautomation.com/t/modbust-tcp-issue/103009/7 "2025-02-27T21:53:19Z")
~~What I see with devices like this is that addresses in between published/supported registers return a data address error instead of returning zeros like well-behaved devices. If you span across such an address, the whole request gets rejected without any way to indicate which address is the problem.~~ I see. Not for this case. ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [February 27, 2025, 9:54pm UTC](https://forum.inductiveautomation.com/t/modbust-tcp-issue/103009/8 "2025-02-27T21:54:25Z")
Yeah I've seen that before too, and certainly more commonly. I just can't tell from his screenshots if that is what's happening - all the tags look good quality to me, just with values going to 0 in some of them. ---
**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 27, 2025, 9:56pm UTC](https://forum.inductiveautomation.com/t/modbust-tcp-issue/103009/9 "2025-02-27T21:56:03Z")
I recall someone reporting that reading addresses of 16-bit ints adjacent to 32-bit floats broke things. Might be something like that.