# Opcua server call back for acknowledgement

**URL:** <https://forum.inductiveautomation.com/t/opcua-server-call-back-for-acknowledgement/82585>\
**Category:** Ignition\
**Created:** [December 1, 2023, 1:59pm UTC](https://forum.inductiveautomation.com/t/opcua-server-call-back-for-acknowledgement/82585 "2023-12-01T13:59:20Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Darshil\_Moradiya](https://avatars.discourse-cdn.com/v4/letter/d/8dc957/32.png) [@Darshil\_Moradiya](https://forum.inductiveautomation.com/u/Darshil_Moradiya)\
**Post date:** [December 1, 2023, 1:59pm UTC](https://forum.inductiveautomation.com/t/opcua-server-call-back-for-acknowledgement/82585/1 "2023-12-01T13:59:20Z")

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hello guys,

 ![ignition](https://us1.discourse-cdn.com/inductiveautomation/original/3X/5/7/57cd8bf2e4eb3bdc3a2fb0d95fed5ef7cb7a3587.png)  
 ![prosys](https://us1.discourse-cdn.com/inductiveautomation/original/3X/1/4/148defe1021edf40a3befad68e59185b3ceba2ca.png)  
 ![server](https://us1.discourse-cdn.com/inductiveautomation/original/3X/8/7/87a06d498d13c9422dac7bcd5a31ace70144b8b6.png)

I am looking for a solution for something similar. I have an OPC UA server connected to an ignition. I have a sensor that shares status values, so I have set an alarm for that status. When an alarm is generated, I have to acknowledge it and send back an acknowledgment to the server. So I have tried first with Prosys opc ua browser to call back for acknowledgment, and there it works perfectly. I have added images for ref, so now I want the same thing: when the alarm generates, I want to send an ACK back to the server from the ignition. and every time an alarm is generated, the event ID value for that alarm is unique, so if I want to send ack back to the server, I have to use that same value for ack. In the image, you can see that. in the prosys browser, value data type is a different hexadecimal byte string, for example: [16]0xb8e743902ec9754cb5ab6d3efb8f86e3. and in ignition value coming in string like:[74, 114, 204, 88, 25, 136, 159, 209, 254, 107, 153, 13, 172, 149, 135, 38]...so please guide me how can acknowledge the alarm from ignition to the server back

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**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:** [December 1, 2023, 2:42pm UTC](https://forum.inductiveautomation.com/t/opcua-server-call-back-for-acknowledgement/82585/2 "2023-12-01T14:42:37Z")

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> [@Darshil\_Moradiya](#):
>
> string like

No, that looks like a java byte array that has been stringified by printing it. That is almost certainly _exactly_ the right object type to include in your method call. (Someone else will have to help you with the method call--haven't done those myself.)