If your Comfort II and Slaves currently are higher than version 5.100 it means that the firmware is flash-based, which means that you can use a UCM05 to upgrade them
Pre-5.100 Comfort II firmware is non - flash and they need a MPU01 to plug in to upgrade the firmware. The new MPU will be flash based so in future you can upgrade by UCM05 and Comfigurator
Upgrading the Main unit using UCM05 does not upgrade thye Slaves, they have to be upgraded separately
The firmware for Comfort and Slave can be obtained from http://www.cytech.biz/upgrades.html
All my units are pre 5.100 so I will get MPU01's for all of them. Flashing the Main board is no problem, I understand the upgrade procedure. There is however no mention of the slave unit upgrades. Do I upgrade the main unit and then transfer the MPU01 to the slave? Doing this 4 times will upgrade all 4 of them or should I somehow transfer my UCM05 to each device individually and upgrade them one at a time?
You have 1 Comfort and 3 Slaves, so you will need 1 MPU-ULT and 3 MPU-SEM
MPU for Comfort and Slaves are different as the firmware for Comfort and slaves are different from each other
Once you plug in the MPUs to their respective boards, you do not need to upgrade them further, as they will have the latest firmware already
It is only in future when new firmware is available that you can use the UCM05 to upgrade the Flash memory on your new MPUs
Are there any issues with running the main board on the current version and not updating the slave? the Main board is currently 5.121 and the slave is 5.033. I will upgrade to ULT 5.145 if it won't cause problems and get a mpu-sem to do the slave later.