User's Manual

QL 420 User’s Guide 43
Communications Port
Signal
Pin# Name Type Description
1 RXD input Receive Data
2 TXD output Transmit Data
3 CTS input Clear To Send from host
4RTS output Request To Send
set high when printer
is ready to accept command
/data
5 GND Ground
6NC No Connect
7 DSR input Data Set Ready
low to high transition turns
printer on, high to low
transition turns printer off
(if enabled)
8 DTR output Data Terminal Ready
set high when printer is on
(set to battery voltage for
“S” versions)
8
7
6
4
2
1
5
3
FIGURE 19 COMMUNICATIONS PORT
(8 pin Circular DIN)
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