2 Installation
22
Alpha Technologies
2.6 Connecting the RS–232 Port
The DB–9 port is a standard feature, but its configuration is different depending upon if a SID or
IID display panel is installed on the unit.
TIPS:
1)
The cable must be less than 50 ft (15m) long and it must be shielded to meet EMI
requirements.
2)
The RS–232 is not isolated. Signal ground is directly connected to the internal logic
ground. Contact Alpha if the external battery connector must be referenced to positive
ground instead of negative ground (the factory default).
Connecting Units With an SID Display Panel:
•
It uses a basic 3–wire line with software handshaking (XON / XOFF).
•
Figure 2.8 shows how to connect the RS–232 port to a standard PC serial port.
•
The parameters are: 1200 baud, 8 data bits, no parity, 1 stop bit.
Connecting Units With an IID Display Panel:
•
The IID RS–232 port uses a nonstandard cable with RTS/CTS signal straight through
and RX/TX signals reversed.
•
The baud rate is operator-configurable.
•
For further information on IID RS–232 applications refer to “Information Management
Using the Intelligent Interface Device” manual (Alpha P/N # 018–029–B0–001).
Figure 2.8
RS–232 Wiring Diagrams
1
2
6
7
8
9
3
4
5
CTS
RTS
TXD
RXD
GND
FOR USE WITH IID
EQUIPPED UNITS
1
TXD 2
RXD 3
4
GND 5
6
RTS 7
CTS 8
9
2 RXD
3 TXD
4
5 GND
6
7 RTS
8 CTS
9
1
UNIT RS-232
SERIAL CONNECTOR
(9-PIN FEMALE)
9-PIN IBM PC
SERIAL PORT
1
TXD 2
RXD 3
4
GND 5
6
RTS 7
CTS 8
9
2 TXD
3 RXD
4 RTS
5 CTS
6
7 GND
24
25
1
UNIT RS-232
SERIAL CONNECTOR
(9-PIN FEMALE)
25-PIN IBM PC
SERIAL PORT
