Rockwell Automation 1769-IT6 Compact I/O 1769-IT6 Thermocouple/mV Input Module - Manual (Page 73)

Rockwell Automation Publication 1769-UM004B-EN-P - March 2010 73
Module Data, Status, and Channel Configuration Chapter 4
Impact of Autocalibration on Module Startup During
Mode Change
Regardless of the selection of the Enable/Disable Cyclic Calibration function, an
autocalibration cycle occurs automatically on a mode change from
Program-to-Run and on subsequent module startups/initialization for all
configured channels. During module startup, input data is not updated by the
module and the General Status bits (S0 through S5) are set to 1, indicating a Data
Not Valid condition. The amount of time it takes the module to start up is
dependent on channel filter frequency selections as indicated in
Channel Update
Time, on page 69 . This is an example calculation of module start-up time.
EXAMPLE Two Channels Enabled for Different Inputs
Channel 0 Input: Type T Thermocouple with 60 Hz filter
Channel 1 Input: Type J Thermocouple with 60 Hz filter
Module Start-up Time
= (Ch 0 Gain Time + Ch 0 Offset Time) + (Ch 1 Gain Time
+ Ch 1 Offset Time) + (CJC Gain Time + CJC Offset Time)
+ (CJC 0 Data Acquisition + CJC 1 Data Acquisition
+ Ch 0 Data Acquisition + Ch 1 Data Acquisition)
= (112 ms + 71 ms) + (112 ms + 71 ms) + (53 ms + 53 ms
+ 53 ms + 53 ms)
= 183 ms + 183 ms + 183 ms + 212 ms = 761 ms