Déscription
The CIO-DIO24/CTR3 combines digital input/output and counters on one board. It has the digital lines common to the PIO-12, PIO-24 and CIO-DIO24 boards, and is also connector compatible with them. In addition, three 16-bit counters allow frequency measurement or event counting, such as monitoring the number of times a door opens or items passing on a conveyor belt. The CIO-DIO24/CTR3 is very easy to program from any language that supports writing to and reading from I/O ports. Two chips control the board functions. An 8255 chip contains the 24 lines of digital I/O and an 8254 chip contains the 3 16-bit counters. The connector carries 24 digital I/O lines plus the counter inputs and outputs. The 8255 digital I/O chip has 24 I/O lines. The chip is configured as three ports. Two ports, A and B, are 8-bits wide. Port C may be an 8-bit port or two 4-bit ports. Individual ports may be configured as input or output, and are written to or read from as a unit. Counter inputs, gates and outputs may be controlled or chained at the connector, or inboard on a counter chaining jumper.