National Instruments NI 9212, Руководство пользователя

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Table 1.
Signal Descriptions
Signal Description
TC Thermocouple connection
TC+ Positive thermocouple connection
TC- Negative thermocouple connection
NI 9212 Connection Guidelines
■
Make sure that devices you connect to the NI 9212 are compatible with the
module specifications.
■
The shield grounding methodology can vary depending on the application.
■
Refer to your thermocouple documentation or the thermocouple wire spool
to determine which wire is the positive lead and which wire is the negative
lead.
Minimizing Thermal Gradients
Changes in the ambient air temperature near the front connector or a thermocouple
wire conducting heat directly to terminal junctions can cause thermal gradients.
Observe the following guidelines to minimize thermal gradients and improve the
system accuracy.
■
Use small-gauge thermocouple wire. Smaller wire transfers less heat to or
from the terminal junction.
■
Run thermocouple wiring together near the TB-9212 to keep the wires at the
same temperature.
■
Avoid running thermocouple wires near hot or cold objects.
■
Minimize adjacent heat sources and air flow across the terminals.
■
Keep the ambient temperature as stable as possible.
■
Make sure the NI 9212 terminals are facing forward or upward.
■
Keep the NI 9212 in a stable and consistent orientation.
■
Allow the thermal gradients to settle after a change in system power or in
ambient temperature. A change in system power can happen when the
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NI-9212