Campbell SDS-122, User Manual

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SDS-122 Serial Data Switch
4
25-Way Switched RS232 Port A
Figure 4 Pin Positions for Switched RS232 Port ‘A’: 25-way Female ‘D’ Type
Connector
The 25-way switched RS232 port (marked ‘RS232 PORT A’ in Figure 1) is a
25-way female ‘D’ type connector, having the following pin configuration:
PIN ABBREVIATION INPUT/OUTPUT
DTE
DCE
1 Frame Ground
2 TX O I
3 RX I O
4 RTS O I
5 CTS I O
6 DSR I O
7 GND
15 External Power Supply I I
20 DTR O I
Other pins are not connected.
Control Port (3-way Screw Terminal)
The control port is a 3-way terminal block with screwed connections. This
terminal block can be unplugged from the unit for ease of wiring. The terminal
connections are marked G, P and M and are used as follows:
TERMINAL CONNECTION
G 0V – It is recommended that a wire is run from this terminal
to the main protective earth point in the system to give
maximum protection from interference and transients.
P In MANUAL mode, this terminal can be pulled high to select
port B. In AUTO mode, when PL41 is fitted, it functions as an
output and will go logic high when port B is being used or logic
low when port A is being used.
M When this line is pulled high, the SDS-122 will be in MANUAL
mode and only the port that is selected by the user (by using the
P terminal) will be active.
SERIAL I/O
13 1
25 14