FC 74 - Calibration Command (NAMM02 - IMAMM03)

The operator initiates, guides and terminates a calibration sequence with the calibration command function code. Function code 74 resides in fixed block 80 and produces no usable

outputs. Enter calibration commands by tuning this block.

 

Outputs:

Blk

Type

Description

80

R

No usable output

 

 

Specifications:

Spec

Tune

Default

Type

Range

Description

S1

Y

0

I

0 - 255

Command calibration operation

S2

Y

0

I

0 - 255

Number of point to be calibrated (1 - 64)

 

 

74.1  Explanation

 

Calibration must be performed when:

 

  1. Initially installing the control and I/O modules.

  2. Replacing the control module.

  3. Changing or replacing an I/O module.

  4. Changing an I/O module address (changing the numbers of the blocks referring to it).

  5. The calibration EEROM is initialized.

  6. Making a change to the leadwire resistance parameter (S9, function code 70).

  7. Changing the cable length between the I/O modules and termination units (S3, function code 71).

 

Calibration can be performed by using internal references generated by the analog master module or externally by zero and full scale calibrations explicitly and in that order. Specification S1 selects the calibration type.

 

Specifications:

 

S1 - COMMAND

Specification S1 is the code that specifies a calibrate operation

on the NAMM02 and IMAMM03 modules.

 

1 = Disable point. A point must be disabled before any calibration can begin. This will prevent calibration related data from being interpreted as process data by the rest of the system. Use disable point when calibrating with a precision source or resistance at the terminal block.

 

2 = Disable I/O module. Use the disable I/O module command when calibrating with the special calibration sockets on the termination units.

 

NOTE: The point or I/O module must be disabled before calibrating (Steps 3 through 9).

 

3 = Perform complete thermocouple I/O module calibration automatically using internal references.

 

4 = Perform thermocouple I/O module external zero-millivolt calibration.

 

5 = Perform thermocouple I/O module external 80-millivolt (for NAMM02 module) or 100-millivolt (for IMAMM03 module) calibration.

 

6 = Perform thermocouple point external zero-millivolt calibration.

 

7 = Perform thermocouple point external 80-millivolt (for NAMM02 module) or 100-millivolt (for IMAMM03 module) calibration.

 

8 = Perform RTD point external 100-ohm calibration.

 

9 = Perform RTD point external 400-ohm calibration.

 

10 = Enable point. A point must be enabled before normal input processing can occur. This action terminates the calibration sequence for a point.

 

11 = Enable I/O module. An I/O module must be enabled before normal input processing can occur. This action terminates the calibration sequence. The I/O module enable is allowed even if the points were disabled individually.

 

12 = Escape. Use the escape command to reset calibration logic in the middle of a sequence (i.e., after taking a zero-volt or 100-ohm measurement).

 

S2 - POINT

Specification S2 is the number of the point on the I/O module to be calibrated.

 

1 < point no. < 64

 

 

Application

 

Monitoring the output provides different responses depending on the interface device. Table 74-1 gives the possible responses from the configuration and tuning module assuming error free operation. Table 74-2 gives the possible responses from the operator interface station or other higher level devices assuming error free operation. The failure of any particular command must be followed up by a read of the calibration status block (block 81, function code 75) to determine the cause.

 

 

Table 74-1. Configuration and Tuning Module Response Table

 

Response Index

Meaning

0

Abnormal condition detected (check calibration status, block 81)

1

Good displayed within 1 sec

2

Good displayed within 30 secs

3

Good displayed within 60 secs

C114

Error encountered

 

 

 

Table 74-2. Operator Interface Station Response Table

 

Response Index

Meaning

0 (error)

Abnormal condition was detected during calibration (refer to calibration status block).

1 (good)

Calibration command block rewritten on OIS console screen with command field (S1) unchanged from operator supplied value.

2 (waiting)

Module busy messages written on OIS console screen.  Operator should display the calibration command block at 30-sec intervals.