Determining Module Update Time; Calculating Accuracy - Allen-Bradley CompactBlock LDX 1790D-T4T0 User Manual

3-12 Module Data, Status, and Channel Configuration for DeviceNet
Determining Module
Update Time

Calculating Accuracy

Publication 1790-UM003A-EN-P
The module update time is defined as the time required for the module to
sample and convert the input signals. Module update time is dependent
on the number of input channels and the input filter selection.
The fastest update time occurs with the 500Hz filter enabled. The
following table shows update times for all filter frequencies.
Table 3.8 Module Update Time
Filter Module Update Time
Frequency
10 Hz 3.0 seconds
25 Hz 1.3 seconds
50 Hz 668 milliseconds
60 Hz 580 milliseconds
100 Hz 383 milliseconds
250 Hz 204 milliseconds
500 Hz 144 milliseconds
Overall accuracy is determined from the combination of the module and
the thermocouple. The total error is the sum of the following:
• module accuracy and error due to temperature
• thermocouple error
• error due to thermocouple lead wire
• CJC error
Module and Temperature Error
The combined module error and error due to ambient temperature is
shown in the table below.
Table 3.9 Module and Temperature Error
Thermocouple Type Error (10Hz Filter) 0 to 55°C
B ±4.2°C
E ±2.5°C
J ±2.8°C
K ±3.3°C
R ±3.6°C
S ±3.6°C
T ±1.3°C
N ±3.1°C