Homebuilt OTGW cannot communicate with Honeywell Round

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Ordered a kit this week at Kiwi-electronics and soldered it myself (not to experienced so that might be one of the causes ) and it's now only partially working.

What is working is the communication with my Daalderop boiler
What is not working is the communication with my Honeywell Round modulation (also tried the wireless opentherm relay BDR88 but that only has leds so not very helpfull for diagnosing)
The Round modulation is booting up but then after +/- 10 second it's flashing to indicate no Ot communication and I also do not see any status change on the OTmonitor nor commands (also not in diagnose mode)

What I've tried so far with the steps from the troubleshooting page:

No IC1, no OK1

powersupply Resistance between X3 terminals: 3.03K

voltage P5 <-> P14 IC1: 4.99V (polarity ok)
Voltage X1: 24.5V
Current X1: 6.41mA
Connect IC1 P3<-->P5 Current X1: 20.8 mA

Plugin OK1 connect X1 to X2

Voltage X2: 16.30V

Connect IC1 socket P2 <-> P14

Voltage X2: 5.10V
IC1 P3 open Voltage IC1 P18 <--> P5: 0.00V
IC1 P3 <-> P5 Voltage IC1 P18 <--> P5: 2.35V

Pull OK1 X1 & X2 still connected

IC1 P18 <-> P5: 0V
OK1 P3 <-> P4: 0.392V

Remove power

OK1 P3 <-> P4: 98.4Ohm

OK1 back in Poweron

R1: 0.67V
R2: 0.39V
R3: 0.86V
D9: 1.25V
D10: 14.23V

OpenthermMonitor displays following lines

R80000100 Read-Data Status:00000001 00000000

Could you please advise what to check next?

[hvxl]

How did you conclude that the communication with your boiler is working? I don't get that impression from the data you presented.

All the measurements you reported look pretty good. The next check you can try is to load the diagnostic firmware and run test #5. If you get more than 1 result for the thermostat, you can also try test #2. If you feel zealous, run test #4 too. Please check the instructions on what to connect to the boiler and thermostat terminals of the gateway for each test.

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Thanks for the pointer! Loaded the diagnostics firmware and ran test 5 and saw that with nothing connected it read 0.00 volts. In another thread somebody had the same test result and you pointed them to R5. When measuring R5 I got around 5V but measuring pin 17 didn't give any result so concentrated on R5 and turns out that with my "baking" skills I managed to fry the circuit board connection between R5 and R6 . As soon as I repaired that connection communication with the thermostat started working so now have a working setup! Thanks for the support.