Model RDG-24 is an intelligent, 24-bit parallel digital-I/O-to-computer interface unit. RDG-24 is enclosed in a steel enclosure for use in hostile environments. There are no switches or jumpers to set to enable half-duplex operation. In RDG-24 there are jumpers to bypass the opto-isolators if you wish, plus there are jumpers to set full-duplex operation if you desire. Digital Inputs may be read individually, in 8-bit bytes, or in 24-bit words at voltages up to 50 VDC. There are also digital software counters on each input. Selectable edges can be counted for up to 65,535 transitions. These counters support Read and Reset commands. Moreover, change-of-state flags can be set on any enabled input bits and can be read via the serial port. This is particularly useful in applications where it is necessary to detect contact closures or openings. This change-of-state detection capability is enabled on a bit-by-bit basis for all bits that are programmed to be inputs. Digital-input sample rate is software programmable from 14 Hz to 1 KHz. Digital Outputs may be programmed individually, in 8-bit bytes, or in 24-bit words. These outputs may be latched, pulsed, or set to free run at a programmed rate. The digital output drivers are open-collector circuits that have 350 mA drive capability at a logic "low". RDG-24 outputs can comply with up to 50 VDC (voltage supplied by you) or, if no external voltage is available, outputs will be pulled up by an internal 10 Kilohm resistor to 5 VDC. The digital-output square wave pulse rate is software programmable from 7 Hz to 500 Hz. A built-in watchdog timer resets the pod if, for some unexpected reason the microcontroller "hangs up" or if the power supply voltage drops below 4.75 VDC. Also, data collected by the pod are stored in local RAM for later access through the computer's serial port. This feature facilitates a stand-alone mode of operation. For example, a portable or laptop computer that has an RS-485 port can be brought to the pod, connected, and collect the data.