Instruction Manual

14 CompactBlock Distributed I/O on PROFIBUS DP Series D
Publication
1791P-IN002B-EN-P - October 2003
Select Termination for the Module
The terminator resistor is provided in the connector. Use the DIP switches in
the connector to select termination for the module. Refer to the illustration
below.
Base Module to Expansion Interface
The base module is linked to the expansion module with an 8-bit parallel bus,
control lines, Vcc and ground connections, a reset/initialization line, and an
expansion presence line. The 8-bit bus is multiplexed so that 16 bits of data (1
for each I/O point) can be transmitted/received with two transfers. The
reset/initialization line is used during initialization of the module. The
presence line is used for the detection of an expansion module at power up
and for a period of each data transfer. Module ID is read over this bus at
power up.
1791P modules supply expansion power via expansion bus as follows:
Expansion power voltage 5Vdc
Expansion power current 100mA
VP (6)
390 ohm
220 ohm
390 ohm
SW in the connector
RxD/TxD-P (3)
RxD/TxD-N (8)
DGND (5)
Switch SW in the Connector
ON Terminator Connector
OFF No Terminator
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