2 2 Amp Proportional Valve Drivers, both normally OFF (DAC channels 1 & 2)
1 unassigned buffered 5V reference output
1 set of three terminals for string pot connection (A/D channel 2)
1 set of three terminals for RTD or thermistor connection (A/D channels 3 & 4)
1 isolated input F-to-V converter (A/D channel 1)
8 250 ma current sink digital outputs for driving solid state relays, etc.
1 PWM output from DAC 3
Connector for jumpers to send power to the M302 board
4 tie point terminals for V+ connection for poppet valves, relays, etc.
Analog input features can be bypassed
2 spare terminals, plus a prototyping area
The EXPv1 expansion board stacks on the expandable version of the Model 302
Data Acquisition System. The Expansion board contains a mixture of interfacing
circuitry suitable for a wide variety of acquisition and control applications. Inputs
can be voltage, current, frequency, or resistance, with accomodation for RTD or
thermistor temperature sensors. Analog Outputs can be voltage, current, or PWM.
The optically isolated current outputs can sink 2 amps or more. Digital outputs can
sink up to 250 ma.
The individual interfacing blocks are based on proven, high performance products
and are designed for use with our 24-bit data acquisition systems. High impedance
analog inputs interface directly to ion selective and pH electrodes. High resolution
allows direct interfacing to bridge sensors or even thermocouples.
Proportional Valve Drivers, two available
DESCRIPTION
Two proportional drive circuits are provided. They are optically isolated power drivers
for solenoids, valves, DC heaters, DC motors, and other DC loads. They output a
proportional current from 0 to 2.5 amps, or more. The current output follows an analog
voltage from analog outputs 1 and 2 on the Model 302 data system.
A proportional valve, a fan motor, and a heating element are examples of loads
that can be controlled with resolution matching the analog control voltage. Expensive
loop controllers can be replaced with improved performance and much lower cost in
many applications.
Output up to 2 amps, or more, at 10 to 24 volts, optically isolated
Input control voltage 0-5 volts
Efficient, so that no active cooling is needed.
Typical modulation frequency 1500 Hz or 4000 Hz factory option
Modulation frequency is preset, but can be set over a wide range
Load can be inductive or resistive
Built-in 5 amp freewheeling diode for inductive loads
Gain is adjustable via on-board trim potentiometer, 0 - 100% range
Output is monotonic
Linearity is excellent over the middle 90% of the range
Counts-to-Volts input, one available
DESCRIPTION
A frequency or pulse stream can be converted to a precise analog
voltage. Resolution is good enough to see a single edge while still being
able to handle 100s of kHz. The input can be from any sort of pulse
or frequency generator, including position sensors and radiation detectors.
A proprietary Sigma-Delta demodulation approach is used for superior
accuracy and stability.
18 bit resolution, high stability counts-to-volts converter
Optical isolation on input
Dual sensitivity ranges
Edge triggered, duty-cycle independent
0.25 second time constant
See the Model 106 for more details
Digital Outputs
Eight current sink outputs are provided. These accommodate up to 30 volts at
250ma continuous current. 100% overcurrent can be sustained for a fraction
of a second.
PWM Output
Analog output number 3 is available as a duty cycle on a screw terminal
on the the expansion card.
Other Input
Circuitry and connection points are provided for RTD or thermistor inputs.
Connections provided for string potentiometer or other ratiometric inputs.
Power connections are provided for powering a bridge circuit or other
powered sensor.
Power Requirement
The expansion card is powered from the Model 302's power supply.
It requires less than 30 ma, so the smallest supplies are adequate.
Loads can be be powered by the same supply, if sufficient, or by
external isolated or unisolated power sources.
Customization
The system is designed to be easy to customize. Contact the factory for
a different mix of features, or entirely new capabilities.
