Detailed description of services -8, Read from variable area -8, Detailed description of services – Rockwell Automation 900 Temperature Controller Communications Functions - Series B User Manual
Page 24: Read from variable area
Publication 900-UM004D-EN-E - July 2010
2-8
Bulletin 900 Communications Procedures 900-TCx (CompoWay/F)
Detailed Description of
Services
Read from Variable Area
This service reads from variable areas.
• Variable Type and Read Start Address
For details on Variable Types and Read Start Addresses, refer to Chapter
3, Communications Data.
• Bit position
Bit accessing is not supported on the 900-TCx. It is fixed to 00.
• Number of elements
Table 2.7
Number of Elements
Process
0000
The read operation is not performed (read data is
not appended to the service response PDU), and
processing ends in normal completion.
Double word
0001…0019 (1…25)
The read operation is carried out, and processing
ends in normal completion.
Word
0001…0032 (1…50)
Read Data
(for number of elements)
Response
Code
4
SRC
2
MRC
2
0
1
0
1
Service Response PDU:
Service Request PDU:
MRC
2
SRC
2
2
2
0
1
0
1
Variable
Type
Read Start
Address
4
Bit
Position
Number of
Elements
4
0
0
Number of elements X 8 or 4