Configuration and Use Manual 59
Configuring Inputs
Configuring System Data Configuring APIConfiguring InputsConfiguring Security & Language
7.6 Configuring the external inputs
External input parameters are used to configure polling. Polling is used to retrieve temperature or
pressure data from an external device over a HART/Bell 202 connection. You may poll for either
temperature or pressure, or both.
Note: Pressure compensation and external temperature are optional. Configure pressure
compensation only if your sensor is subject to pressure effect and if the operating pressure is
significantly different from calibration pressure. External temperature compensation is used to
provide an external temperature value for the petroleum measurement application or the enhanced
density application. If you have core processor v2.1 or earlier, the external temperature data is used
for all calculations that require temperature values. If you have core processor v2.2 or later, the
external temperature data is used only for calculation of the derived variable in enhanced density
applications or the CTL (Correction for Temperature on volume of Liquids) value in petroleum
measurement applications. To determine your core processor version, use the Applications List from
the View menu (see Section 17.5.9).
Note: If you poll for temperature or pressure, ensure that the external measurement device is accurate
and reliable.
To set up polling, you must configure the external input parameters and you must also ensure that the
primary milliamp output has been wired for HART protocol (see Section 3.4). The external input
parameters are listed and defined in Table 7-17.
Table 7-17 External input parameters
Variable Default Description
Polling control Do not poll You can configure polling control for an external temperature device, an
external pressure device, or both:
• Do not poll – polling will not occur.
• Poll as primary – The Series 3000 device will poll the external HART device
as a primary master. Choose this option if the external device will probably
be accessed by another device acting as a secondary master (e.g., a HART
Communicator).
• Poll as secondary – The Series 3000 device will poll the external HART
device as a secondary master. Choose this option if the external device will
probably be accessed by another device acting as a primary master.
If polling both a temperature device and a pressure device, you must configure
the same polling control method for both. In other words, you cannot poll one
external device as a primary master and the other external device as a
secondary master. However, you can disable polling for one device, then poll
the other device as either a primary or secondary master.
Polling variable None Select the process data to be polled through this polling variable:
• Temperature
• Pressure
•None
External tag NONE Enter the HART tag of the external device to be polled for temperature or
pressure.
Pressure
compensation
(1)
Disable • Select Enable to enable pressure compensation.
• Select Disable to disable pressure compensation.
Pressure units PSI Select the pressure unit that is used by the remote device that you are polling
for pressure.
Flow factor
(1)
0.0000 % per PSI The percent change in the flow rate per PSI. Not all sensors or applications
require a pressure correction factor for flow. For the value to be used, see the
product data sheet for your sensor, then reverse the sign of the value listed for
pressure effect for flow (e.g., if the pressure effect is 0.000004 % per PSI,
enter a pressure correction factor of –0.000004 % per PSI).
