Hercules III User Manual Rev A.2
www.diamondsystems.com
Page
24
6.11
Serial Ports 1, 2, 3, 4 (J18)
J18 is a 40-pin header that provides access to serial ports 1, 2, 3 and 4. The pinout depends on the protocol
selection. The pinouts below show all ports with the same protocol; however each port may have its own protocol
selection.
RS-232 Configuration
RS-485 Configuration
RS-422 Configuration
Port 1
DCD 1
1
2
DSR 1
1
2
1
2
RXD 1
3
4
RTS 1
3
4
3
4
TXD 1
5
6
CTS 1
5
6
5
6
DTR 1
7
8
RI 1
7
8
7
8
GND
9
10
NC
9
10
9
10
Port 2
DCD 2
11
12
DSR 2
11
12
11
12
RXD 2
13
14
RTS 2
13
14
13
14
TXD 2
15
16
CTS 2
15
16
15
16
DTR 2
17
18
RI 2
17
18
17
18
GND
19
20
NC
19
20
19
20
Port 3
DCD 3
21
22
DSR 3
NC
21
22
NC
NC
21
22
NC
RXD 3
23
24
RTS 3
TXD/RXD+ 3
23
24
TXD/RXD- 3
TXD+ 3
23
24
TXD- 3
TXD 3
25
26
CTS 3
GND
25
26
NC
GND
25
26
RXD- 3
DTR 3
27
28
RI 3
NC
27
28
NC
RXD+ 3
27
28
NC
GND
29
30
NC
GND
29
30
NC
GND
29
30
NC
Port 4
DCD 4
31
32
DSR 4
NC
31
32
NC
NC
31
32
NC
RXD 4
33
34
RTS 4
TXD/RXD+ 4
33
34
TXD/RXD- 4
TXD+ 4
33
34
TXD- 4
TXD 4
35
36
CTS 4
GND
35
36
NC
GND
35
36
RXD- 4
DTR 4
37
38
RI 4
NC
37
38
NC
RXD+ 4
37
38
NC
GND
39
40
NC
GND
39
40
NC
GND
39
40
NC
Connector type:
Standard 2.54mm dual row straight pin header with 4mm posts and gold flash plating
Diamond Systems cable number C-DB9M-4 provides a standard DB9 connector at each end and mates with this
header.
6.12
External Battery (J20)
Connector J20 is used to connect an external battery for maintaining the real-time clock and CMOS settings
(BIOS settings for various system configurations). The battery voltage for this input should be 3-3.6VDC. The
current draw averages under 4µA at 3V. Use cable 6981011 with J20.
1
Battery input (+)
2
Ground
Connector type:
Vertical .1” pitch friction lock connector
Connector on board:
Tyco 640456-2 pin header or equivalent
J20 External Battery Connector (end view)