# Send wrong command to modbus tcp

**URL:** <https://forum.inductiveautomation.com/t/send-wrong-command-to-modbus-tcp/58152>\
**Category:** Ignition\
**Tags:** ignition81\
**Created:** [April 7, 2022, 9:35am UTC](https://forum.inductiveautomation.com/t/send-wrong-command-to-modbus-tcp/58152 "2022-04-07T09:35:56Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Niranjan\_Phadke](https://avatars.discourse-cdn.com/v4/letter/n/54ee81/32.png) [@Niranjan\_Phadke](https://forum.inductiveautomation.com/u/Niranjan_Phadke)\
**Post date:** [April 7, 2022, 9:35am UTC](https://forum.inductiveautomation.com/t/send-wrong-command-to-modbus-tcp/58152/1 "2022-04-07T09:35:56Z")

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Following is the address definition for delta plc

Prefix : Y  
Start : 0  
End : 12  
Step : None  
Unit id : 1  
Modbus Type : Coil  
Modbus address : 1281

It was showing bad tags so checked the command passed to modbus.

Ignition is generating following command

000A00000006010105000310

First six Message id : 000A00000006  
Unit id : 01  
Function code : 01  
Start Address : 0500 = 1280 Decimal  
Number of Address : 0310 = 784 Decimal

Even though number of address configured is 12 so message should get 0C00 instead of 0310.

Please help. Thanks in adavance.

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**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 7, 2022, 12:31pm UTC](https://forum.inductiveautomation.com/t/send-wrong-command-to-modbus-tcp/58152/2 "2022-04-07T12:31:34Z")

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You probably have additional coils defined and the driver is trying to access them all in one large request. If you don’t want this behavior you can disable the “Span Gaps” setting for that device connection.

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**Author:** ![Niranjan\_Phadke](https://avatars.discourse-cdn.com/v4/letter/n/54ee81/32.png) [@Niranjan\_Phadke](https://forum.inductiveautomation.com/u/Niranjan_Phadke)\
**Post date:** [April 7, 2022, 1:16pm UTC](https://forum.inductiveautomation.com/t/send-wrong-command-to-modbus-tcp/58152/3 "2022-04-07T13:16:14Z")

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Thank You. Kevin. Which check and confirm back.

I checked and it working fine. Thanks a ton.

Original message : 010105000310  
After unchecking Span Gaps  
New Message : 010105000001