M172* writing to BACnet device object instance

[obscuresc]

Hi,

I'm using a TM172PDG18R on 668.14 with EcoStruxure Machine Expert HVAC v1.6.0, and am connecting using Yabe v1.3.0.0.

I've noticed that on boot of the PLC, the BACnet device object identifier (IEC side) has both the object type and the object instance fields set i.e. the identifier will be set to 33554462, meaning that the object type is 8, the object instance is 30.

If I change the device instance via Yabe, Yabe raises an unhandled exception, and the IEC-side device object type goes to 0. The device instance will be successfully changed, and the PLC is visible at the new device instance.

Is this behaviour a bug on the PLC or in Yabe? I would not have thought the device object type would be editable over the wire. I have tried to emulate this behaviour using another BACnet client but I was unsuccessful.

Thanks.

[FedericoM · Accepted solution]

Hello,

I think it's normal since the Device changed it's own ID.

Note that if you change the Device ID from BMS, you have to store it into EEprom and use it to set it as new Device ID in case of reboot.