MSI MS-9A78B1, Manual, Page: 14 / 54

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Overview MS-9A78B1
6
RS-232/422/485 Serial Port: COM1 (0V/5V/12V)
The serial port is a 16550A high speed communications port that sends/
receives 16 bytes FIFOs. It supports barcode scanners, barcode printers, bill
printers, credit card machine, etc.
1 5
6 9
RS-232
PIN SIGNAL DESCRIPTION
1
2
3
4
5
6
7
8
9
NDCD
NSIN
NSOUT
NDTR
GND
NDSR
NRTS
NCTS
VCC
Data Carrier Detect
Signal In
Signal Out
Data Terminal Ready
Signal Ground
Data Set Ready
Request To Send
Clear To Send
5V or 12V selected by jumper
RS-422
PIN SIGNAL DESCRIPTION
1
2
3
4
5
6
7
8
9
422 TXD-
422 RXD+
422 TXD+
422 RXD-
GND
NC
NC
NC
NC
Transmit Data, Negative
Receive Data, Positive
Transmit Data, Positive
Receive Data, Negative
Signal Ground
No Connection
No Connection
No Connection
No Connection
RS-485
PIN SIGNAL DESCRIPTION
1
2
3
4
5
6
7
8
9
485 TXD-
NC
485 TXD+
NC
GND
NC
NC
NC
NC
Transmit Data, Negative
No Connection
Transmit Data, Positive
No Connection
Signal Ground
No Connection
No Connection
No Connection
No Connection