Rockwell Automation 1762-IT4 Thermocouple/mV Input Module - Manual (Page 65)

Publication 1762-UM002A-EN-P - July 2002
Module Data, Status, and Channel Configuration 3-35
separate ADC self-calibration and offset calibration cycles only if their
filter configurations are different than those of previously calibrated
channels.
Following all input channel calibration cycles, the CJC sensor channel
receives a separate ADC self-calibration cycle. The time added to this
cycle is determined by the filter setting for the CJC, which is set to the
lowest filter setting of any input configured as a thermocouple. If no
enabled input channel is configured for a thermocouple, no CJC
calibration cycle occurs. See Table 3.6 below for channel and CJC
sensor ADC self-calibration times as well as channel offset calibration
times.
Calculating Module Update Time
To determine the module update time, add the individual channel
update times for each enabled channel and the CJC update time if any
of the channels are enabled as thermocouple inputs.
Table 3.6 Calibration Time
Type of Calibration 10 Hz 50 Hz 60 Hz 250 Hz 500 Hz 1 kHz
ADC self-calibration
(Channels 0 through 3) 603 123 103 27 15 9
Offset calibration
(Channels 0 through 3) 303 63 53 15 9 6
ADC self-calibration
(CJC sensor) 603 123 103 27 15 9
EXAMPLE
1. Two Channels Enabled for Millivolt Inputs
Channel 0 Input: ±50 mV with 60 Hz filter
Channel 1 Input: ±50 mV with 500 Hz filter
From Table 3.5, Channel Update Time, on page 3-34:
Module Update Time
= Ch 0 Update Time + Ch 1 Update Time
= 53 ms + 9 ms
= 62 ms