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© Sealevel Systems, Inc. 8012e Manual | SL9225 12/2022
Input Port Pin Assignments (DB-44 Female)
Port A Bit
Port A Pins
0
2,40
1
3,41
2
4,36
3
5,37
4
6,38
5
7,42
6
8,43
7
9,44
The above diagram is representative of how dry contact inputs (or current / voltage sources) can be
monitored by the optically isolated inputs. When switch 1 above is closed, it will allow current to flow from
the power source, into pin 3 of the DB-44, through the optocoupler, out pin 41, and back to the power source.
If the current flow is between 2 and 20 mA, this input will be read as logic “0”. All the input associated with
all open switches will be read as logic “1”.
In the diagram above, pins 36-38, and 40-44 are joined, providing a common return path for the
optocouplers. In this case, the interconnections are being made on the connector itself. In the DB-37
diagram below the return path is supplied external to the connector. Also for electrical isolation, each input
/ output pair can be powered from an individual power source with no common present.
