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Rockwell Automation 1794-IT8,D17946.5.7 Thermocouple/Millivolt Input Module User Manual

Page 31

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4–5

Writing Configuration to and Reading Status from your Module with a Remote I/O Adapter

Publication 1794-6.5.7 – April 1997

00

01

02

03

04

05

06

07

08

09

10

11

12

13

14

15

Decimal Bit

00

01

02

03

04

05

06

07

10

11

12

13

14

15

16

17

Octal Bit

9

Overrange Bits

Underrange Bits

10

0

0

0

0

0

Bad

Cal

Cal

Done

Cal

Range

0

Diagnostic Status

Pwr

Up

Bad

Structure

CJC
over

CJC

Under

Thermocouple/mV Input Module (1794-IT8) Write

Dec. Bit

15

14

13

12

11

10

09

08

07

06

05

04

03

02

01

00

Octal Bit

17

16

15

14

13

12

11

10

07

06

05

04

03

02

01

00

Write Word 0

8-Bit Calibration Mask

Cal
Clk

Cal hi
Cal lo

Filter Cutoff

FDF

Data Type

1

Thermocouple 3 Type

Thermocouple 2 Type

Thermocouple 1 Type

Thermocouple 0 Type

2

Thermocouple 7 Type

Thermocouple 6 Type

Thermocouple 5 Type

Thermocouple 4 Type

Where:

FDF = fixed digital filter bit

Word/Bit Descriptions for the 1794-IT8 Thermocouple/mV
Input Module

Word

Decimal Bit

(Octal Bit)

Description

Read Word 0

00–15 (00–17)

Reserved

Read Word 1

00–15 (00–17)

Channel 0 Input data

Read Word 2

00–15 (00–17)

Channel 1 Input data

Read Word 3

00–15 (00–17)

Channel 2 Input data

Read Word 4

00–15 (00–17)

Channel 3 Input data

Read Word 5

00–15 (00–17)

Channel 4 Input data

Read Word 6

00–15 (00–17)

Channel 5 Input data

Read Word 7

00–15 (00–17)

Channel 6 Input data

Read Word 8

00–15 (00–17)

Channel 7 Input data

Read Word 9

00–07 (00–07)

Underrange bits – these bits are set if the input signal is below the input channel’s minimum range.

08–15 (10–17)

Overrange bits – these bits are set if 1), the input signal is above the input channel’s maximum range,
or 2), an open detector is detected.

Read Word 10

00 (00)

Cold Junction sensor underrange bit. – this bit is set if the cold junction temperature is below 0

o

C.

01 (01)

Cold Junction sensor overrange bit. – this bit is set if the cold junction temperature is above 70

o

C.

02 (02)

Bad Structure – this bit is set if an invalid thermocouple type is selected.

03 (03)

Powerup bit – this bit is set (1) until configuration data is received by the module.

04–06 (04–06)

Critical Error bits – If these bits are anything other than all zeroes, return the module to the factory for
repair

07 (07)

Unused – set to 0

08 (10)

Calibration Range bit – set to 1 if a reference signal is out of range during calibration

09 (11)

Calibration Done bit – set to 1 after an initiated calibration cycle is complete.

10 (12)

Calibration Bad bit – set to 1 if the channel has not had a valid calibration.

11–15 (13–17)

Unused – set to 0