# Modbus Descrete Input Addressing **URL:** \ **Category:** Ignition\ **Created:** [April 27, 2017, 2:01pm UTC](https://forum.inductiveautomation.com/t/modbus-descrete-input-addressing/14152 "2017-04-27T14:01:45Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Dustin\_VanKeuren](https://avatars.discourse-cdn.com/v4/letter/d/b782af/32.png) [@Dustin\_VanKeuren](https://forum.inductiveautomation.com/u/Dustin_VanKeuren)\ **Post date:** [April 27, 2017, 2:01pm UTC](https://forum.inductiveautomation.com/t/modbus-descrete-input-addressing/14152/1 "2017-04-27T14:01:45Z")
I am new to Ignition, so please bear with me. I am talking to a device over Modbus TCP. I connect to it fine, and even able to read HR, IR, and C registers just fine. I am having issues reading the DI registers however. I am getting Received response with ExceptionCode: 0x03 (IllegalDataValue). I am not sure what the issue is. The tags I created are Boolean (I did try over types just to see if it had an effect). The addressing (from the manual) is [MBDevice]DI1 (one of the tags) I also tried [MBDevice]DI1.0 I must be missing something simple here. ---
**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:** [April 27, 2017, 2:09pm UTC](https://forum.inductiveautomation.com/t/modbus-descrete-input-addressing/14152/2 "2017-04-27T14:09:19Z")
Do you know what the DI valid addresses for this device are? Typically this ExceptionCode is returned when you read a location that the device has no data for. ---
**Author:** ![Dustin\_VanKeuren](https://avatars.discourse-cdn.com/v4/letter/d/b782af/32.png) [@Dustin\_VanKeuren](https://forum.inductiveautomation.com/u/Dustin_VanKeuren)\ **Post date:** [April 27, 2017, 2:19pm UTC](https://forum.inductiveautomation.com/t/modbus-descrete-input-addressing/14152/3 "2017-04-27T14:19:10Z")
Yes, the device manual lists the DI registers (1 - 60) and what they are for. I suppose it is possible that the device needs to be configured properly. I was only given the task to communicate with it. Being unfamiliar with the device and Ignition, I was not sure where to start troubleshooting. ---
**Author:** ![dturner](https://avatars.discourse-cdn.com/v4/letter/d/90ced4/32.png) [@dturner](https://forum.inductiveautomation.com/u/dturner)\ **Post date:** [April 27, 2017, 4:08pm UTC](https://forum.inductiveautomation.com/t/modbus-descrete-input-addressing/14152/4 "2017-04-27T16:08:10Z")
What type of device is it? ---
**Author:** ![Dustin\_VanKeuren](https://avatars.discourse-cdn.com/v4/letter/d/b782af/32.png) [@Dustin\_VanKeuren](https://forum.inductiveautomation.com/u/Dustin_VanKeuren)\ **Post date:** [April 27, 2017, 4:15pm UTC](https://forum.inductiveautomation.com/t/modbus-descrete-input-addressing/14152/5 "2017-04-27T16:15:19Z")
I believe it is a controller for a rectifier. ---
**Author:** ![dturner](https://avatars.discourse-cdn.com/v4/letter/d/90ced4/32.png) [@dturner](https://forum.inductiveautomation.com/u/dturner)\ **Post date:** [April 27, 2017, 7:00pm UTC](https://forum.inductiveautomation.com/t/modbus-descrete-input-addressing/14152/6 "2017-04-27T19:00:52Z")
The reason why I asked is because some devices actually have a the information stated in Hex or have an offset for the memory map. The first device that comes to mind for me is the MGE/APC UPS modules. ---
**Author:** ![Dustin\_VanKeuren](https://avatars.discourse-cdn.com/v4/letter/d/b782af/32.png) [@Dustin\_VanKeuren](https://forum.inductiveautomation.com/u/Dustin_VanKeuren)\ **Post date:** [April 27, 2017, 7:16pm UTC](https://forum.inductiveautomation.com/t/modbus-descrete-input-addressing/14152/7 "2017-04-27T19:16:22Z")
Excellent point. I am in contact with the manufacturer that sent us the board. I will follow up here with what I find. Someone else may find the information useful. ---
**Author:** ![Dustin\_VanKeuren](https://avatars.discourse-cdn.com/v4/letter/d/b782af/32.png) [@Dustin\_VanKeuren](https://forum.inductiveautomation.com/u/Dustin_VanKeuren)\ **Post date:** [April 28, 2017, 2:44pm UTC](https://forum.inductiveautomation.com/t/modbus-descrete-input-addressing/14152/8 "2017-04-28T14:44:15Z")
The issue turned out to be the device, and it was indeed that I was trying to read registers that were not configured in the device I was trying to read from. I assumed all the input registers in the documentation were active. I removed the tags pointed to the invalid registers and everything seems to be working fine.