Frequently Asked Questions

Readings Fail when Printer Attached

The system operates normally in both local and remote operation until a printer is attached to the parallel port. All telemetry readings become zero or status off even though the system is not printing.

This usually indicates a ground issue. The printer probably has a grounded plug in which case installing a ground lifter often solves the problem.

The RFC-1 power supply must be floating for the telemetry system to function properly. Parallel printers should have separate grounds for data and frame. However, some printers connect the two ground points and cause this to happen.

The RAK-1 employs optical isolation on data signals to avoid this condition but it occurs at a small number of installations.