Heater and Sensor Connections for ITC-502 All three channels wired the same way. The pin connections below are specific to GE/Carbon resistors (including Cernox) and for Si/GaAs Diodes. 9-pin D connectors: cable is male. pin # 1 Input High (V-) 2 Input Low (V+) 3 Input GND (linked to pin 2, isolated from chassis) 4 I+ 5 I- 6 Heater Output +ve 7 Heater Output -ve 8 not used 9 Chassis Ground