User`s guide

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Notice that this interface provides a positive voltage on pin 4 of the DB9 connector. Also notice
that pin 5 should be grounded, but it is run through a low value resistor for protection.
This is the interface type provided for both COM1 and COM2 on the RUC board.
The second type of serial interface is called a DCE interface and is the type of interface used
with peripheral equipment. Recognize that pin 4 needs a voltage on it in order for this circuit to
work.
DB9
5
4
3
2
1
DCE
Peripheral End
PPIM Board
TX
RX
GND
DTR
Device -i.e., PIM
Serial Cable
N/C