Variable type and read start address, Bit position, Response code – Rockwell Automation 900 Temperature Controller Communications Functions - Series B User Manual
Page 28: Composite read from variable area -12, Composite read from variable area
Publication 900-UM004D-EN-E - July 2010
2-12
Bulletin 900 Communications Procedures 900-TCx (CompoWay/F)
Composite Read from Variable Area
This service reads in order the contents of specified addresses in the variable
area.
Service Request PDU
Service Response PDU
Note: The read data is read together with the variable type in the order specified by the command.
Variable Type and Read Start Address
For details on variable types and read start addresses, Refer
to Communications Data on page 2-3.
Bit Position
The 900-TCx controllers do not support bit access. Fixed to “00.”
Number of Read Data Items (Variable Type + Read Data)
Response Code
Normal completion
Table 2.13
Read Data Length
Number of Read Data Items
For double word
20 max.
For word
25 max.
MRC SRC
0 1 0 4
0 0
2
2
2
2
4
0 0
2
2
4
Variable
type
Read
address
Bit
position
Variable
type
Read
address
Bit
position
Variable
type
Response
code
Variable
type
Read data
2
2
MRC SRC
0
1 0
4
4
Number of elements
×
8 or 4
2
2
Read data
Number of elements
×
8 or 4