Hercules-EBX CPU User Manual V1.02
Page 25
RS-485 Configuration:
Port 1
1
2
3
4
5
6
7
8
9
10
Port 2
11 12
13 14
15 16
17 18
19 20
Port 3
NC
21 22
NC
TXD/RXD+
3
23 24
TXD/RXD- 3
GND
25 26
NC
NC
27 28
NC
GND
29 30
DIO C
Port 4
NC
31 32
NC
TXD/RXD+
4
33 34
TXD/RXD- 4
GND
35 36
NC
NC
37 38
NC
GND
39 40
DIO D
Table 15: J18 – RS485 Serial Port Connector Pinout
Signal Name
Definition
DE-9 Pin
Direction
RS-485:
TXD/RXD+,
Differential Transceiver Data (HIGH) pin 2
Bi-directional
TXD/RXD-
Differential Transceiver Data (LOW) pin 7
Bi-directional
Connector Part Numbers
J18 Connector on CPU board:
Phyco 2120-40S
J18 Mating Cable Connector:
Standard 2x20 0.1” Female Ribbon cable header
4.15 External Battery Connector – J20
1
Batter input
2
Ground
Table 16: J20 – External Battery Input
The external battery voltage maintains the on-board Real-Time Clock, as well as the on-board
CMOS settings (BIOS settings for various system configurations). The battery voltage for this
input should be 3-3.5V. The current draw averages under 4uA at 3V. Note that the on-board
battery, this battery, and an additional external battery input on the Utility Connector (J7 above)
are all possible sources for this power. Whichever battery has the highest voltage will see the
majority of the current draw, which is minimal regardless. Note that there must be a battery
voltage input for the default power-up mode (see page 34).
Connector Part Numbers
J20 Connector on CPU board:
Digi-Key Corp. A1921
J20 Mating Cable Connector:
2-pin female header