1 pin 1 protective ground (pg)
2 2 transmit data (txd)
3 3 receive data (rxd)
4 4 request to send (rts)
5 pin 5 clear to send (cts)
6 6 data set ready (dsr)
7 7 signal ground (sg)
8 20 data terminal ready (dtr)
bridge between 4 and 5 means alternative rts to cts. cables with bridges at printer side (4 to 5 and 20 to 6) for older pms lower than pm-40a4) can also be used!
additional information
after power-on dtr and rts are activated and the printer is ready to receive data.
xoff is sent, when the interface buffer has only space left for 256 more characters.
xoff is sent again, at a level of 128 characters buffer space. further incoming data will be stored until the interface buffer is full. all data sent in addition will get lost.
xon is sent when the interface buffer provides space for a minimum of 512 characters.
xon/xoff can only be sent successfully when cts and (dsr) is at active state.
xoff will be sent immediately if local mode is entered.
xon is sent again, if local mode is left and a minimum of 512 byte interface buffer is available.