CS, CH commands reset after 2 minutes

[AndrewFG]

I am using the Nodo OTGW connected to a Viessmann boiler. Currently I am using it without a thermostat. Instead I am using the OpenHAB binding to send CS and CH commands to the boiler. The odd thing that I am experiencing is that if I send a CS or CH command value to the boiler, the value becomes active in the boiler for a while, but after about two minutes the value resets. For example if I send CH=1 the boiler becomes enabled, but after about 2 minutes it becomes disabled again. => Any idea what is going on?

[hvxl]

See the change log for Firmware 5.2, specifically:

• Limit the validity of a CS command. A remotely set control setpoint expires after just over a minute. This is a safety feature to prevent runaway heating when the controlling program loses its connection, or crashes.

A device controlling the boiler will normally update the control setpoint quite frequently to account for changing conditions. My thermostat does it about every 4 seconds. But if you want to keep the same control setpoint for a long time for some reason, just repeat the CS command every 30 seconds or so. Think of it like a heartbeat.

Alternatively, you can downgrade to firmware 5.1.

[AndrewFG]

^
Aha. Brilliant. Many thanks.