Can you tell me about proper grounding procedures with a 1553 board?

If you are using a 1553 board and are physically on the aircraft, then both ends of the 1553 bus should be grounded to the aircraft.

However, if you are not physically on the aircraft, then one end of the loop should not be grounded, because a grounding loop could occur.

If both ends are grounded this is the potential problem: The aircraft is grounded to the floor ties, and the 1553 board is then grounded to the computer. These are different grounds, and there can be as much as 300 volts difference between these two ties. The result will be incorrect measurements.

This is relevant to all boards, but is especially important for mobile boards such as PCMCIA cards and PCI boards, because these are most likely to be taken to the aircraft by engineers.