(supported rs-232c protocols) - full duplex local connection
this protocol uses the following signal lines:
1 pin 1 protective ground (pg)
2 2 transmit data (txd)
3 3 receive data (rxd) (with internal pull-up) 1)
4 5 clear to send (cts) (with internal pull-up) 1)
5 7 signal ground (sg)
6 20 data terminal ready (dtr)
the ready / busy dtr protocol uses the data terminal ready line to control the transmission of data from the host to prevent a buffer overflow.
the signal lines txd (pin 2) and cts (pin 5) are only necessary if the device status report is required (see picture "connection for unidirectional transfer mode").
1 version 1 - connection for unidirectional transfer mode
cables with bridges at printer side (4 to 5) for older pms (lower than 1) pm-40a4) can also be used!
2 version 2 - connection full duplex transfer mode
control the transmission of data from the host to prevent a buffer overflow. the ready / busy dtr protocol uses the data terminal ready line to
3 version 3 - pc connection for full duplex transfer mode
bridge between 7 and 8 on pc side means alternative rts to cts.
additional information
after power-on dtr is activated and the printer is ready to receive data.
dtr is deactivated when the interface buffer has only space left only for 256 more characters. further incoming data will be stored until the interface buffer is full. all data sent in addition will get lost.
dtr is activated again if there is a free interface buffer space of 512 characters.
dtr is immediately deactivated, if local mode is entered.
it is activated again, if local mode is left and a minimum of 512 bytes interface buffer is available.
2.2 xon / xoff
this protocol requires the signal lines.
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 activestate. 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.