ISA Bus Eight-Bit 16-Input A/D and Counter/Timer Card

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Model AD8-16 (alternate part number ADA-8) is an economical, multiplexed, eight-bit Analog-to-Digital Converter (A/D) and Counter-Timer card for ISA-bus computers. It accepts up to eight differential or 16 single-ended analog inputs (jumper configured). AD8-16 requires a full-size expansion slot. All connections are made through a standard 50-pin connector. Base I/O address selection is via dip switch.

Analog inputs are multiplexed, amplified, held by a sample and hold amplifier, and then digitized by an eight-bit A/D converter. Amplifier gain is selected by software and can differ from channel to channel.

Full scale voltage ranges are ±128 mV, ±5V, 0-255mV, and 0-10V. When operating in the bipolar ranges, the digital output is available in 2's complement or offset binary format. The end-of-conversion signal can be used to interrupt the computer when configured by jumper. You can select from IRQ levels 2-7. The interrupt request is automatically cancelled when the A/D data are read.

There are two 8-bit Digital-to-Analog converters on this card. These D/A's output ranges are -10V to +10V and are intended to drive 10 kilohm or greater load. Maximum output current is 5 mA.

Model AD8-16 also accepts up to eight TTL-level or switch inputs. High inputs may be from 2.5 to 24 VDC or an "open." All digital inputs are pulled up to 5 VDC by 1 kilohm resistors on the card. Low inputs should not exceed 0.8 VDC.

This card also provides eight discrete digital outputs. Each output can sink up to 24 mA with zener diode protection at 5.6 VDC. At system turn-on or reset the digital outputs are tri-stated and remain so until the computer writes to them. For interface to your application program, there are also two highly useful capabilities: Digital Output Read which allows a bit-by-bit readback of the current digital output byte and Command Readback which provides readback of the Control Register.

Model AD8-16 also contains an 8254 timer-counter consisting of three 16-bit counters. These counters may be loaded and read by software. You have complete ability to configure gates, clocks, and outputs either at the I/O connector or via jumpers on the card. A clock at 1/2, 1/4, 1/8 or 1/16 the computer clock rate is available for counter operation. Also, the color oscillator frequency can be used. Alternatively, an external clock may be applied via the I/O connector.

Features

• 16 Single-ended or 8 differential analog inputs
• Eight-bit resolution
• Over 16,000 conversions per second
• Programmable scan rate and voltage ranges
• Two 8-bit analog outputs
• Three programmable counter/timers
• Eight digital inputs
• Eight digital outputs
• +5V output, 1 amp, fused
• Designed, made, supported, and manufactured in the USA