Detailed Descriptions Of Services; Read Variable Area - Omron KM50 Communications Manual

Section 2 CompoWay/F Communications Protocol

2. 3 Detailed Descriptions of Services

■ Read Variable Area

This service reads from the variable area.
• Service Request PDU
MRC SRC
0 1 0 1
2 2
(Numbers below the frame are the number of bytes.)
• Service Response PDU
MRC SRC
0 1 0 1
2 2
(1) Variable Type and Read Start Address
For details on variable types and read start addresses, refer to SECTION 3 CompoWay/F
Communications Data.
(2) Bit Position
Bit access is not supported by the KM50-C.
Always use 00.
(3) Number of Elements
Specify the number of variables to read.
No. of elements
0000
0001 to 000B
* If the read start address is in the variable area and the read end address (read start
address + number of elements) exceeds the last address in the variable area, the data to
the end of the variable area will be read and processing will end in a normal completion.
Example 1: The last address is specified as the read start address and two elements is
specified.
Read start address →
Read end address →
Only the value at the last address will be read.
2-8
Variable Read start address
type
2 4
Response code Read data (for the number of elements)
4
The read operation is not performed (i.e., read data is not appended to the service
response PDU), and processing ends in a normal completion.
Up to 11 elements (0B hex) is read, and processing ends in a normal completion.
Address
****
****
Bit
No. of elements
position
0 0
2 4
8 × n (n = 0 to 11)
Processing
Variable area
********
← Last address
********