The Allen-Bradley 1771-IGD PLC-5 TTL Input Module can be used in a Series A or B 1771-A1B, -A2B, -A3B, -A3B1, and -A4B chassis. The module is also compatible in a 1771-AM1 or -AM2 I/O chassis.
The operator can use any TTL device that meets the output logic level specification of -0.2VDC to +0.8VDC (low), and 2.0VDC to 5.25VDC (high).
The module contains input filtering to limit the effects of voltage transients caused by contact bounce and/or radiated electrical noise. The delay due to filtering is less than 1ms.
For maximum noise immunity, the output of the TTL device should have a pull-up resistor of 1Kohm (typical). Add an external pull-up resistor to the output terminals of the device, if necessary. If a pull-up resistor is added, the TTL device should maintain the low state requirement of -0.2VDC to +0.8VDC with the increased load.
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