# Writing to C coils on Koyo PLCs

**URL:** <https://forum.inductiveautomation.com/t/writing-to-c-coils-on-koyo-plcs/5117>\
**Category:** Ignition\
**Created:** [September 7, 2012, 4:54pm UTC](https://forum.inductiveautomation.com/t/writing-to-c-coils-on-koyo-plcs/5117 "2012-09-07T16:54:34Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Paul](https://avatars.discourse-cdn.com/v4/letter/p/bbe5ce/32.png) [@Paul](https://forum.inductiveautomation.com/u/Paul)\
**Post date:** [September 7, 2012, 4:54pm UTC](https://forum.inductiveautomation.com/t/writing-to-c-coils-on-koyo-plcs/5117/1 "2012-09-07T16:54:34Z")

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Good day all,  
Problem: ‘C’ coils used in Koyo PLC’s (D250) do not allow Ignition to write to them. The coil addresses are clean, meaning the PLC is not over writing them in ladder logic anywhere. Further, the ‘Y ‘address can be written to, by opening up the SQL tag browser and checking the value box. However if you try that with a ‘C’ address, it will stay selected for a moment, then uncheck itself. Anyone have any idea what’s going on?

Thanks,

-Paul

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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:** [September 7, 2012, 4:58pm UTC](https://forum.inductiveautomation.com/t/writing-to-c-coils-on-koyo-plcs/5117/2 "2012-09-07T16:58:56Z")

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I assume you’re using the Modbus driver here… Is there anything in the logs?

Try turning ‘WriteSingleCoilRequest’ and ‘WriteMultipleCoilsRequest’ loggers to TRACE, under System \> Console \> Levels, doing the write, and then exporting the logs and sending them in/posting them here.

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**Author:** ![Paul](https://avatars.discourse-cdn.com/v4/letter/p/bbe5ce/32.png) [@Paul](https://forum.inductiveautomation.com/u/Paul)\
**Post date:** [September 7, 2012, 5:29pm UTC](https://forum.inductiveautomation.com/t/writing-to-c-coils-on-koyo-plcs/5117/3 "2012-09-07T17:29:48Z")

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Will do, the project is now off site, making a trip necessary, but no less important.

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**Author:** ![Paul](https://avatars.discourse-cdn.com/v4/letter/p/bbe5ce/32.png) [@Paul](https://forum.inductiveautomation.com/u/Paul)\
**Post date:** [September 18, 2012, 8:49pm UTC](https://forum.inductiveautomation.com/t/writing-to-c-coils-on-koyo-plcs/5117/4 "2012-09-18T20:49:19Z")

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Did not have the time to properly solve this topic, instead went down the road of bit to word read and writes. That did get the driver and PLCs to correctly respond. Will have to leave this for another day, when one can get the hardware into the shop.

-Paul