Kevin, it works. Address byte with mark, data with space, PARMRK on the receive side. Indicators 1, 2 and 4 answered first try, number 3 wanted a 2 ms gap after the address, which I added. The children appeared in Hermetry on the first v1/gw/telemetry. Keeping Jason’s STM32 idea as plan B if the line people complain.