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Overview
The transmitter can poll an external temperature device for current temperature data. The
external temperature value is used only by the petroleum measurement application or the
concentration measurement application. If you do not have one of these applications, do
not set up polling for temperature.
Tip
To obtain value from using an external temperature value, the external measurement device must
be reliable and must provide more accurate data than is available from the sensor.
Prerequisites
Polling requires HART protocol over the Bell 202 physical layer. Ensure that the primary mA
output on your transmitter has been wired for HART protocol, and that the external
measurement device is accessible over the HART network.
Procedure
1. Select Polled Variable 1 or Polled Variable 2.
2. Set Polling Control.
Polling Control determines how the transmitter will access the external
measurement device.
Option
Description
Primary
The transmitter is the only device that will access the external measurement
device as a primary master.
Secondary
Another device on the network will access the external measurement device as
a primary master.
Tip
If you set up polling for both temperature and pressure, use the same Polling Control option for
both. If you do not, Primary will be used for both devices.
3. (ProLink II only) Click Apply to enable the polling controls.
4. Enter the device tag of the external measurement device.
5. Set Process Variable to Temperature.
Postrequisites
Verify that the transmitter is receiving the external data. To do this:
• Using ProLink II, click ProLink > Process Variables and check the External Temperature
value.
• Using the Field Communicator, select Overview > Primary Purpose Variables.
Need help? If the value is not correct:
Integrate the meter with the control system
Configuration and Use Manual 121