Hengstler TP3 protocol

[chris_cb_uk]

Has anybody come across this protocol? I have the following Counter with RS232 out https://www.hengstler.de/gfx/file/shop/counter/signo_727/Datasheet_727_1_e.pdf
From my digging it uses a TP3 protocol, the datasheet tells me the RS232 spec but only "mask" commands to get reading which is for a printer.  I thought I'd ask here to see if anybody has experience before I put a probe on between a computer to sniff the commands to reproduce.
Chris