Measurement Computing WBK Options - Manual (Page 108)

WBK17, pg. 30 987996 WBK17, Counter/Encoder Module
Digital Outputs
The WBK17 has 8 fully programmable digital outputs. Each output has an open-drain DMOS FET
(Double-diffused Metal Oxide Semiconductor Field Effect Transistor) that can sink up to 150 mA and is
capable of directly driving relays.
Digital Output Port
The digital output port can be read back as part of the scan group of an acquisition. If the DMOSFET is
never turned on by the WBK17, then the digital output port can be used as an input port. An external driver
can drive any of the digital output bits high or low, as long as the WBK17”s DMOSFET is not turned on.
The digital outputs can be directly updated by application software at any time. The digital output port has
an 8-bit Mask byte associated with the digital update byte. The output port will be updated if the
corresponding bit in the Mask byte is a 1. Otherwise the output port bit will be left unchanged.
The digital outputs can be updated based on the condition of any input channel value(s). Up to 16 set points
(each with two 16-bit compare values, an 8-bit digital output port byte, an 8-bit mask byte, and a control
byte) can be assigned to a channel. When a set point has been programmed (count value, period,
pulsewidth, position, or velocity) the two 16-bit values are compared, in real-time, to the measured value for
that channel. When the comparison condition is met, the output port is updated instantaneously. Valid
conditions include greater than value, less than value, inside the window, and outside the window. Since
each set point has an 8-bit mask byte, any or all of the digital output bits can be updated. With 16 setpoints
per channel complex updating schemes can be defined to meet the most demanding application
requirements.