The circuits use an 82C55A PPI with mode 0 supported. Ports A, B and C are buffered with 74ABT245 transceivers and pulled up to 5V. The optional 82C54 has three-sixteen bit down-counters within one chip. These counters are useful for making frequency outputs, measuring frequency of square waves, pulse width outputs, pulse width measurements etc. Software drivers are provided on CD.
48 Parallel Bits of Digital I/O Type 82C55 PPI mode 0
Compatible with Opto-22 type Solid State Module Racks
Two 24 bit groups (two 8 bit ports, two 4 bit ports each group)
All bits are buffered, 64mA sink, 32m A source
I/O pulled up to 5V for Contact Monitoring, Pulldown resistors are an option (factory installation)
Fused (resetable) 5V available on pin 49 of each group
I/O connectors: Two Industry Standard 50 pin headers plus one ten-pin header for counter timer