Hi, Craig,

They are certainly aware, because I had numerous communications with them on this subject. The last contact I had with them they were unable to replicate this in their lab, and were puzzling over this problem. As for the firmware, the latest for the ATU is 4.06, and this is the version that should be used with the serial switch. The problem would seem to be in the serial switch itself. You are correct, the function of the serial switch was to allow both a PC and the ATU to communicate with the radio at the same time so that logging programs, FT8 programs, etc, and the C-M ATU could all share access to the radio. In my case I used an Icom IC-7600, as well as my Elecraft KX3, and my Flex 6400M, all with the same result - the serial switch did not forward the communications from the PC to the radio, so that only the C-M frequency query commands were received by the radio. After a lot of investigation on my part C-M requested me to return my serial switch, and they eventually refunded my money despite the fact that I had said that I was quite prepared to await a replacement with updated firmware. I am not sure if the serial switch's firmware can be user updated like the C-M ATU. Having written this sort of software myself, I can well appreciate the technical problems. When I have had to do this professionally before I retired, I opted for a 'store and forward' algorithm so that you could interleave the various messages and responses and keep track of which message was destined for what device. This becomes even more challenging when attempting to communicate with an Icom radio using its CI-V interface as you now have to deal with a CDMA protocol, which will add further interest to the proceedings. It is certainly possible, but I suspect that C-M may well have to have a re-think as to how they are dealing with this in their serial switch. As I say, stay tuned...

Adrian 5B4AIY