A logical axis is a definition used by the PMAC to specify a geometric axis of movement to a PMAC motor number.
An example of a physical and logical axis definition is as follows. The left azimuth motor is assigned to PMAC Motor #1, PMAC physical axes 1 and 2, and PMAC logical axis X in coordinate system 1. The assignment looks like this:
The PMACS reside in a VME chassis and
communicate with the antenna computer through dual-port RAM and
VME mailbox registers.
The PMACs may also be accessed through an on-board serial port.