The GC-04 DB-9 I/0 Breakout board is a great complement to the GeckoDrive four axis G540 Stepper Drive system. It provides an easy way to connect to the G540 VFD and input terminals without the need for soldering.
The GC-04 BOB has two 9 pin D-Type connectors that are in keeping with the G540s use of DB9 connectors.
GC-04 Rev1 Datasheet