Have 4 (old) YN-622-C and a Canon 7D and steer a YN568EX and a Canon EX580, everything works just fine.
Since the purchase of a Canon EOS 7D Mark II I could the YN-622-C no longer use because Syncproblemen.
Unfortunately, you can not install update firmware at the YN-622-C.
Thanks to the YN-622-TX with firmware 1:05 now everything goes back without any problems.
Very clearly, a lot of setting, good workmanship.
It is best to read before buying the online available PDF document by.
Remote shutter release possible! Two Fernauslösekabel are settled. Is triggered by a YN-622-C, habs but not yet tried.
Firmware can be updated via USB, but unfortunately only with a PC.
Buy recommendation !!