Emerson Process Management 1500 manual 6.6.3Interaction with the update rate

Optional Transmitter Configuration

6.6.3Interaction with the update rate

Flow and density damping values depend on the configured Update Rate (see Section 6.7). If you change the update rate, the damping values are automatically adjusted. Damping rates for Special are 20% of Normal damping rates. See Table 6-2.

Note: The specific process variable selected for the Special update rate is not relevant; all damping values are adjusted as described.

6.7Configuring the update rate

The update rate is the rate at which the sensor reports process variables to the transmitter. This affects transmitter response time to changes in the process.

There are two settings for Update Rate: Normal and Special.

•When Normal is configured, most process variables are polled at the rate of 20 times per second (20 Hz).

•When Special is configured, a single, user-specified process variable is reported at a faster rate, and all others are reported at a slower rate. If you set the update rate to Special, you must also specify which process variable will be updated at 100 Hz. Polling for some process variables and diagnostic/calibration data is dropped (see Section 6.7.1), and the remaining process variables are polled a minimum of 6 times per second (6.25 Hz).

Not all process variables can be used as the 100 Hz variable. Only the following process variables can be selected:

•Mass flow rate

•Volume flow rate

For the Model 1500 transmitter with the filling and dosing application, Special is the default, and the 100 Hz variable is automatically set to the variable configured as the fill flow source (mass flow rate or volume flow rate).

For filling and dosing applications, Micro Motion recommends:

•Use Special for all “short” applications (fill duration less than 15 seconds).

•Use Normal for all “long” applications (fill duration of 15 or more seconds).

For all other applications, Micro Motion recommends using the Normal update rate. Contact Micro Motion before using the Special update rate for other applications.

Note: If you change the Update Rate setting, the setting for damping is automatically adjusted. See Section 6.6.3.

40 Micro Motion® Model 1500 Transmitters with the Filling and Dosing Application