OM-USB-TEMP-AI User's Guide
Signal I/O Connections
18
Wiring configuration
You can connect a TMP36 (or equivalent) semiconductor sensor using a single-ended configuration, as shown
in Figure 10. The OM-USB-TEMP-AI also provides
+5V
and
GND
pins for powering the sensor.
Figure 10. Semiconductor sensor measurement configuration
The software outputs the measurement data as a 32-bit floating point value in either voltage or temperature.
Digital I/O connections
You can connect up to eight digital I/O lines to the screw terminals labeled
DIO0
to
DIO7
. You can configure
each digital bit for either input or output. All digital I/O lines are pulled up to +5V with a 47 k_ resistor
(default). You can request the factory to configure the resistor for pull-down to ground if desired.
When you configure the digital bits for input, you can use the OM-USB-TEMP-AI digital I/O terminals to
detect the state of a TTL-compatible device. Refer to the schematic shown in Figure 11. If you set the switch to
the +5V input, DIO0 reads
TRUE
(1). If you move the switch to GND, DIO0 reads
FALSE
(0).
Figure 11. Schematic showing switch detection by digital channel DIO0
Caution!
All ground pins on the OM-USB-TEMP-AI (pins 9, 19, 22, 27, 30, 33, 36, 39, 49) are common
and are isolated from earth ground. If a connection is made to earth ground when using digital I/O
and conductive thermocouples, the thermocouples are no longer isolated. In this case,
thermocouples must not be connected to any conductive surfaces that may be referenced to
earth ground.
For general information regarding digital signal connections and digital I/O techniques, refer to the
General
Guide to Signal Connections
(available on our web site at
www.omega.com/manuals/manualpdf/M4830.pdf
).
