AccuRange High Speed Interface ISA and PC-104 Formats Users Manual
The AccuRange High Speed Interface is an interface board that takes samples from the AccuRange 4000 optical rangefinder. Two models are available. One model plugs into an IBM-PC or compatible ISA or EISA bus. The other model is PC/104 compatible. Samples come over the bus in an 8 byte format that includes a 19 bit range value and 1 byte values for signal strength, ambient light, and sensor internal temperature as well as status and general purpose input bits. These inputs, along with external enable/disable control of sampling, allow precise synchronization with external events.
The ISA/EISA board has an IBM PC form factor, and will fit in a half-length PC ISA slot. The PC/104 board conforms to the PC/104 specification for a 16-bit stackthrough module. Data is transferred over an 8 bit I/O port, with the address selected with on-board jumpers.
The interface board operates by measuring the range-dependent pulse width output of the AccuRange 4000. To use the 4000 with the High Speed Interface, the Current Loop option must not be installed in the sensor. Each pulse on the pulse width output is timed on the Interface board by a timer with a clock rate of 80 MHz. The sample rate of the interface is therefore controlled by the sample rate for which the 4000 is configured. Since the pulse width output can be set to repeat at up to 50 KHz, that is the maximum sample rate of the interface.
The data collected by the high speed interface is not scaled or calibrated in any way. It can be used to create calibrated distance output using software modules and tables supplied with the interface or though user-written algorithms. The data can be used to calculate distance as each sample is collected, although the more typical application will collect a batch of samples and create distance readings from the entire group after high-speed collection is finished.
Other features of the interface include memory buffer empty, half full, and overflow status indicators, external sample start/stop control, and three general purpose input bits that allow synchronous recording of events while sampling. The board can also be ordered with power control circuitry for two small motors. This is not full servo control, but it allows motor power to be programmed. If the motors have encoders, the encoders may be sampled with the sensor data to provide position information in the sample stream in scanning systems. Each motor can be driven with up to 2 amps at 12 to 48 volts. Power for the motors must be supplied to the board, where it is pulse-width modulated (ISA/EISA model only) or DC level controlled (depending on the configuration ordered) according to the programmed power level.
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