Continuous Parameter Value Read - Allen-Bradley 1203 Series User Manual

B–14 Supported Block Transfer Messages
Continuous Parameter Value
Read
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Continuous Parameter Value Read reads a continuous list of
parameters beginning with the starting parameter number.
PLC Block Transfer Instruction Data
PLC request instruction length: 4 words
Drive response instruction length: 5 – 64 words
Figure B.9 Message Structure
PLC Request
Message Length
Header Word 0
4
PLC Decimal Value
Header Word 1
1
Number of Parameter
Header Word 2
Values to Read
Starting Parameter
Data Word 3
Number
Message Operation
This function specified in the request will read a consecutive group of
parameter values from the device, beginning with the starting
parameter number defined in Word 3 of the request. The number of
parameters to be read is defined in Word 2 of the request. The values
will return in the response, beginning with Word 4. If an error has
occurred in reading any of the parameters, Word 1 of the response
will return a value of -32767 and the response word for that parameter
will return a status word instead of a parameter value.
Drive Response
Header
Message Length
5 – 64
Word 0
PLC Decimal Value
Header
1 — Message OK
Word 1
–32767 — Message Error
Data
Number of Parameter
Word 2
Values to Read
Data
Starting Parameter
Word 3
Number
Data
Value 1
Word 4
or Error Code
Data
Value 2
Word 5
or Error Code
Data
Value 3
or Error Code Word 6
• •
• •
• •
•
•
•
•
•
•
Data
Value 60
or Error Code Word 63