How to properly handle ADS error 1812: Device Notify Handle Invalid (Onlinechange, Release handle and get a new one)

Beckhoff / ADS

Beckhoff protocol to communicate with TwinCAT devices.

MIT License

519 stars 197 forks source link

How to properly handle ADS error 1812: Device Notify Handle Invalid (Onlinechange, Release handle and get a new one) #234

Open xin-tsla opened 2 months ago

xin-tsla commented 2 months ago

Hi All, Wondering when encounter this error, it seems not easy to create a new one, the reason is that when receiving the handle id, there is no context info of which path in PLC we could re-create handle id for. Is there any way to know which path for the handle it to be able to re-create? Thanks!

soberschmidt commented 2 months ago

Hi, I would recommend to persist the PLC symbol on creation of the handles to cover this scenario. Furthermore I would observe the online change counter (Tc3 symbol path: TwinCAT_SystemInfoVarList._AppInfo.OnlineChangeCnt) and the symbol version (ADS Read command with IndexGroup ADSIGRP_SYM_VERSION (0xF008), Offset 0, size = 1 byte). If one of both will change (e.g. online change), I would recommend to release all handles/notifications and create new ones.

xin-tsla commented 2 months ago

Hi @soberschmidt , Thanks for the info! I will give it a try.

xin-tsla commented 4 weeks ago

Hi @soberschmidt , Wondering when TwinCAT_SystemInfoVarList._AppInfo.OnlineChangeCnt will be changed to 0? How twincat know the client side release all handles and reset the counter to 0? Thanks