Connect Digital Ports - Intab PC-Logger 2100 User Manual

5

CONNECT DIGITAL PORTS

The digital ports are multifunctional. The same pins are used for status input,
counter input and alarm output. This makes it absolutely necessary to exercise
utmost care when connecting external equipment to them.
The schematic diagram below shows the details of one of these ports (P1).
Ports P2 and P3 are identical but do not have the output transistor (the parts
within dashed lines).
Definitions:
A "1" is defined as a shorting of the input/output to ground.
A "1" therefore corresponds to 0V on the input/output.
An unconnected port, consequently, is seen by the logger as a 0 (zero).
NOTE!
Note that the digital output of P1 has the digital output transistor across it. This
will cause contention if it is set to a 1 (see definition above) when there is a
signal coming in to the input. Make doubly sure that the digital output is set to 0
(zero) before using the digital input.
Also note that the 10nF capacitor limits the frequency response of the input to
1000Hz.
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5 CONNECT DIGITAL PORTS