Table of Contents
Advertisement
Chapter 6
In addition, the software returns the value SENSOR_IS_OPEN (99999 decimal) for any
channel that was configured for a thermocouple input and has either an open thermocouple
or no thermocouple connected to it. This value is returned anytime a voltage greater than 100
mV is measure on the input, since this value is greater than any legitimate thermocouple
voltage.
If the channel is configured for a voltage input (not a thermocouple type), the Open (OPN)
LED never lights and the SENSOR_IS_OPEN value is not returned. Instead, the voltage value
is returned. If no input is connected to the channel, the software returns a value of
approximately 0.7 V due to the open thermocouple detection pull-up circuit.
RTD Channels
For channels that support RTDs, you can attach a voltage input or any of the following RTD
types in a mix and match fashion: Platinum 100 (Pt100), Platinum 500 (Pt500), or Platinum
1000 (Pt1000) RTD using an European alpha curve of 0.00385 or an American alpha curve of
0.00392. The supported temperature measurement range for these RTD types is –200 C (–328
F) to 850 C (1562 F). You can also measure a resistance value between 0 and 4k Ohms, if
desired. (Refer to
measurements.)
By default, all channels are configured for voltage inputs. You can specify the RTD types for
channels using the DT-Open Layers Control Panel applet, described on
QuickDAQ application, or by using an API call in your application program
Notes: In a mix-and-match system, it is easy to accidentally mismatch the software and
hardware configuration for a channel. Therefore, it is recommended that you pay particular
attention when configuring channels, since the resultant errors may be not large enough to
notice initially, but may be significantly larger than the accuracy specification for the
instrument.
Since each channel has its own 24-bit A/D, analog inputs are measured simultaneously. Refer
to
page 96
Input Ranges
The input voltage range that is supported by your TEMPpoint, VOLTpoint, or MEASURpoint
instrument depends on the specific instrument model that you purchased, as shown in
Table
92
page 92
for information on the supported input range for voltage
for more information on specifying the channels for a scan.
4.
page
40, the
Advertisement
Table of Contents
