HP ProBook 6550b - Serial (Select Models Only); Universal Serial Bus

Serial (select models only)
Pin Signal
1 1 Data carrier detect
2 Received data
3 Transmitted data
4 Data terminal ready
5Signal ground
6 Data set ready
7 Request to send
8 Clear to send
9 Ring indicator
Universal Serial Bus
Pin Signal
1 +5 VDC
2Data
3 Data +
4Ground
188 Chapter 8 Connector pin assignments