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28
Siemens Building Technologies
Cerberus Division
12
Appendix D: GW-21 Rev. A
12.1
The connection board
The connection board has two connectors to insert the CPU and I/O board in.
On the board there are two DB9 D connectors for the two serial ports (UARTs 1 and 2).
UART 2 is a full modem port, i.e. all the standard modem signals for a DB9 connector
are foreseen. UART 1 lacks RI (Ring Indicator) and DCD (Data Carrier Detector) sig-
nals.
UARTs 3 and 4 are accessible through screw connectors located on the right side of
the connection board. Only the TX, RX and GND signals are available.
UARTs 5 and 6, if the expansion board is installed, are accessible through the screw
connectors from 31 to 36 on the connector block on the left side of the connection
board.
On the same connection board there are the two power supply blocks. Each block has
three pins: the central one is the ground, the two laterals are marked + and -. You must
connect here the voltage source (10 to 30 V d.c.).
E1481b
06.2000
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