First, you need to make sure you have a properly configured
MDC system. You can find the areas to set up MDC systems in the tree menu. Then, in each
conventional analog personality, you should be able to choose a signaling protocol for both transmitting and receive. For MDC decode, assign the desired system to a personality under the receive section. If you want to send out MDC when you transmit as well, make sure to also assign that system to the personality under the transmit section. Please note that if you only assign an MDC system under the receive section, you will only decode MDC and not transmit it *UNLESS* you engage talk around.
This works for my XPR4550. If someone else sees something I am missing, please speak up