mjc506We recently had a new Grant ASHP installed, replacing our old oil boiler. It would nice to be able to monitor the heat pump activity and performance.
The Grant ASHP itself (external unit) has terminals marked RS485, which I had hoped would use ModBus to communicate. Unfortunately, I could detect no activity, so perhaps this has to be enabled in software somehow. The manuals contain no details.
The install does, however, include a 'remote control', which is mounted inside the house, and connected to the external unit by twin core cable, through which it received power and, I assume, data.
As the RS485 connections on the external unit do not seem to be activated, and as reading data from the internal remote control would be more convenient, I intend to focus on this.
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I was reading the manual for what guesswork suggests is the original Japanese version of this heat pump (Chofu AEYC-1043XU and related models) and that says "Terminal 15-16-32 : RS485 Mod Bus" (on the external unit PCB) is enabled by setting installer mode parameter group 51 and code 15 to 0=disable and 1=enable. Worth a try and see if you can sniff anything interesting out of the modbus?
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