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OMB-DAQ-TC-RACK User's Guide
Functional Details
14
Figure 5. Digital input connection example
Digital outputs/temperature alarms
The OMB-DAQ-TC-RACK has 32 digital outputs which are
open-drain
. Each DO bit has a 100
kΩ pull-up
resistor and can sink up to 100 mA for direct drive applications. Use the eight
PULL-UP ENABLE – DOUT
slide
switches to enable or disable the 5 V pull-up option.
Figure 6. Digital output connection example
Optionally, you can configure each digital output as an alarm for each TC input. When an alarm is enabled, its
associated output line is driven to the appropriate state determined by the alarm options and input temperature.
You can also use the alarm outputs to control a device or application that indicates when a temperature
threshold has been exceeded.
When its pull-up is disabled, a DO bit can be used to control a device needing up to 15 V (user-provided)
@ 100 mA. If the device needs more voltage/current than this, use a OMB-DAQ-TC-RACK-controlled
MOSFET
(user-provided) to control higher voltages and currents.
Depending on the MOSFET used, the OMB-DAQ-TC-RACK can control up to 50 VDC @ 80 A.
Figure 7 shows a relay requiring 24 VDC @ 100 mA controlled by a OMB-DAQ-TC-RACK digital
output/alarm. The MOSFET driving the signal to the relay can handle up to 14 amps, 50 volts DC.
2
Metal-oxide semiconductor, field-effect transistor that uses an induced electrical field to control current through the device.
Either negative or positive gate voltages can be applied to control the current.