PowerMaster 30: RS232 (CP2102) Port Inactive Until Pull-Up Resistor Added

[DrBobadob]

Hi,
I’d like to share some troubleshooting experience when wiring up my PowerMaster 30 with a USB RS232 module (CP2102). I was surprised to not find this when searching around. Please comment if I got this wrong? At least my set-up is working with this fix.

I was not able to establish a link just connecting gnd, Tx and Rx between the alarm panel and USB interface. The RS232 port was just sending random 00, 58 or 80, and not responding to ack request.
When also connecting 3.7 V, I managed to establish an unstable connection. The integration was starting up but constantly loosing the panel.
I noticed that my old PowerLink 3 (“broadband”) module was using a connection between the two outer pin in the lower row of the IP connector (picture). I speculate that this seam to be a pull up resistor, that I measured to 12.5 kohm on the PL3, to identify that the broadband module is connected (?).
I tried to patch a 55kohm resistor between the pins (this was the best I could find at home and it seems to work). The lower left pin on the panel seem to be isolated with 145 kohm to both gnd as well as 3.7 V, I would expect that my 55 kohm is in the higher range for this pull-up patch to be stable (?).

With this pull up patch I could disconnect the 3.7 V between the panel and USB supplied RS232 interface, avoiding interference between the different regulators at each side.
With only gnd, Rx and Tx connected to RS232 and patching the outer pins in the lower row on the panel, this resulted as an identified broadband module and the link became stable.

Hope this is helpful!

Other findings on the way:
When connecting both a GSM Module and the RS232 interface to HA. In communications configuration:

• 1st report channel: Broadband (important or the integration drop down to safe mode “download only”)
• 2nd report channel: GPRS
  -Dual report: Broadband & GSM