Carrier XCT 7 40VCC727FQEE Operation & Installation Manual page 8

COM2
Gateway address 1-32 can be set to connect VRF models
COM3
Gateway address 1-128, Connect to gateway "40VCAR17FQEE"
COM6
Reserved
fire alarm
COM5
ModBUS-RTU centralized
control data interface
COM4
Connect to a third-party gateway,
gateway address: 1-128
COM1
Gateway address 1-32 can be set to connect VRF models
7