For more in depth details on the Molex MX123 connector series that is used on e.g. the IQAN-MC4x-series, the Molex user manual is recommended reading.
The IQAN accessories repair-kit for Molex MX123 connector has a user manual with some more compact and specific information:
Use a separate switch when starting/restarting the IQAN controller, avoid using the Molex MX123 connector to restart an IQAN-MC4x module. What usually happens then is that the power pins make contact before the IdTag pins.
This can be observed as the 3:2 IdTag error blink code on the MC4x module; when IQANrun is used for diagnosing it will give an error message indicating [No address tag].
Customer support service by UserEcho