Cable Assemblies Control Unit IV Reference Manual
B-6 529-0004 Ver.3
Null modem cable with 25-pin to 9-pin connector (crossover)
To connect the Control Unit’s 9-pin COM 3 port to a modem or other DCE device that has a
25-pin port, you will need a null modem cable with one male 25-pin connector and one male
9-pin connector. Note that this cable is not provided with the Control Unit. The pin
assignments in the table below are shown for reference purposes.
Table B-6: Null modem cable with a male DB-9 and a male DB-25 connector
Male DB-9, to be connected to
Control Unit’s COM 3 (DCE)
Male DB-25, to be connected to
modem’s port (DCE)
Signal (flow)
9-pin
connector
25-pin
connector
Signal (flow)
TX (input) 2 — 3 RX (input)
RX (output) 3 — 2 TX (output)
GND 5 — 7 GND
B.3 Cable assembly for redundancy systems
The Control Unit’s
BACKUP
port is not an RS-232 port. Therefore, you must use a special
redundancy cable provided by Electroline so that the two Control Units will operate correctly
in a redundancy system.
The redundancy cable used on the
BACKUP
port has some crossover wires to ensure
communication (see Table B-7). Pin 1 is the rightmost pin on the top row of the female
BACKUP
port on the Control Unit. The pins are numbered from right to left and from top to
bottom.
Table B-7: Control Unit’s
BACKUP
port (DB-9)
Pin Signal Direction
1 Presence Input
2 Presence Output
3 Feedback Input
4 Feedback Output
5 Configuration Input
6 Ground --
7 Second unit status Input
8 Second unit status Output
9 Not used --
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