Allen-Bradley Compact 1769-IR6, User Manual

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Publication 1769-UM005A-EN-P
4-32 Module Data, Status, and Channel Configuration
Impact of Autocalibration and Lead Wire Compensation on Module
Startup
Regardless of the selection of the Enable/Disable Cyclic Calibration and
Enable/Disable Cyclic Lead Calibration functions, an cycle of both of
these functions 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 until the calibration and compensation cycles are complete.
During this time the General Status bits (S0 to S5) are set to 1, indicating a
Data Not Valid condition. The time it takes the module to startup is
dependent on channel filter frequency selections and other items defined
in the previous sections. The following examples show how to calculate
the module startup time.
EXAMPLE
1. Six Channels Enabled with Same Configurations
All 6 Channels: 100W Platinum 385 RTD, 1.0 mA current
source, 60 Hz filter
Module Startup Time
= (6-step Calibration Time + Current Source Calibration Time)
+ (Lead Wire Compensation Time x 6 channels)
+ (Channel 0 through 5 Data Acquisition Time)
= (504 ms + 482 ms) + (53 ms x 6) + (53 ms x 6)
= 986 ms + 318 ms + 318 ms = 1622 ms = 1.622 seconds
2. Six Channels Enabled with Different Configurations
(worst-case startup time)
All 6 Channels: 100W Platinum 385 RTD, 1.0 mA current
source, 60 Hz filter
Module Startup Time
= [(6-step Calibration Time x 6 channels) + Current Source
Calibration Time] + (Lead Wire Compensation Time for
Ch 0 to 5 x 3) + (Channel 0 to 5 Data Acquisition Time)
= [(504 ms x 6) + 482 ms] + (449 ms x 3)
+ (303 ms + 63 ms + 53 ms + 15 ms + 9 ms + 6 ms)
= 3506 ms + 1347 ms + 449 ms = 5302 ms = 5.302 seconds