I have an Atomos Shogun Studio 2 that can only be remotely controlled by RS-422. Atomos says that it uses Sony 9-Pin Protocol and that several JL Cooper control surfaces will work with it. The JL Cooper devices are very expensive and huge to boot, so I hoped to be able to use a USB-to-serial converter to save money and space. My thought was to cobble something together with Companion and a Stream Deck to trigger records.
My issue is that despite using the correct connection settings as specified in the Sony 9-Pin protocol spec detailed here, I only ever get NAK (11 12) responses back from the device. At least getting a valid error code back from the device tells me that the connection works and it hears the commands being issued, even if the syntax is somehow wrong.
I'm using Termite in hex mode to communicate with the deck at 38400 baud, 8-O-1. I'm trying to trigger a record by sending the REC command in hex (20 02, with a checksum of 22).
I've been barking up Atomos' tree for some hints to no avail so far. The various pieces of documentation on the protocols provide precious little in the way of actual, practical examples of what the syntax looks like. Does anyone with experience from the old days when VTRs were commonplace know the secrets for talking to these devices via serial?