Null Modem Cable Pin Assignments - HP Compaq t1010 Supplementary Manual

Table 48–1 outlines the pin assignments for a 9-pin serial port to a
25-pin serial port null modem cable.
Table 48–1:
25 Pin
2 (transmit data)
3 (receive data)
4 (request to send)
5 (clear to send)
6, 8 (data set ready, carrier detect)
7 (ground)
20 (data terminal ready)
✎
All other pins on either connector of the cable are not used.
Administrators Guide
Null Modem Cable Pin

Null Modem Cable Pin Assignments

Assignments
9 Pin
2 (receive data)
3 (transmit data)
8 (clear to send)
7 (request to send)
4 (data terminal ready)
5 (ground)
6, 1 (data set ready, carrier detect)
48
48–1