Hercules-EBX CPU User Manual V1.02
Page 24
4.14 Serial Port I/O Connector – J18
J18 is 40-pin header that provides access to the 4 on-board serial ports for Hercules-EBX. The
first two serial ports are always configured to meet RS232 standards; the last two serial ports are
software configurable as either RS232 or RS485. All four serial ports are independently enabled
and the last two serial ports can be independently configured between the two modes of operation
(RS232 versus RS485).
Diamond Cable Assembly Number
C-DB9M-4
connects this header to 4 DE-9 Male connectors
(for direct connection to RS232C signaling). The following tables list the signals for the
appropriate mode of operation, as well as the DE-9 pin numbers to which these signals are wired.
Port 1
DCD 1
1
2
DSR 1
RXD
1
3
4
RTS 1
TXD
1
5
6
CTS 1
DTR
1
7
8
RI 1
GND
9
10
N/C
Port 2
DCD 2
11 12
DSR 2
RXD
2
13 14
RTS 2
TXD
2
15 16
CTS 2
DTR
2
17 18
RI 2
GND
19 20
N/C
Port 3
DCD 3
21 22
DSR 3
RXD
3
23 24
RTS 3
TXD
3
25 26
CTS 3
DTR
3
27 28
RI 3
GND
29 30
N/C
Port 4
DCD 4
31 32
DSR 4
RXD
4
33 34
RTS 4
TXD
4
35 36
CTS 4
DTR
4
37 38
RI 4
GND
39 40
N/C
Table 14: J18 – RS232 Serial Port Connector Pinout
Signal Name
Definition
DE-9 Pin
Direction
RS-232C:
DCD
Data Carrier Detect
pin 1
Input
DSR
Data Set Ready
pin 6
Input
RXD
Receive Data
pin 2
Input
RTS
Request To Send
pin 7
Output
TXD
Transmit Data
pin 3
Output
CTS
Clear To Send
pin 8
Input
DTR
Data Terminal Ready
pin 4
Output
RI
Ring Indicator
pin 9
Input
N/C Not
Connected ---
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