WattMaster WCC II - Manual (Page 225)

Section 5: Installation Guide
WCC II Operator’s Guide
Operator Interfaces 5-23
Sequence of Operation
When the SAT II controller makes COM to H, 24 VAC is supplied
to the “HEAT” terminal on the PI board which causes the DC
voltage supplied by the PI board to increase at the preset rate.
When the SAT II controller makes COM to C, 24 VAC is supplied
to the “COOL” terminal on the PI board which causes the DC
voltage supplied by the PI board to decrease at the preset rate.
When both the COM to H and COM to C terminals are open on
the SAT II controller, the DC voltage supplied by the PI board will
remain at its present value.
Typical PI-Board Wiring Diagram