Siemens SIMATIC MV550 S Operating Instructions Manual page 116

Process interfacing via an automation system (PLC, PC)
9.3 Control with Ident profile
Command: Read match string
● The "Read match string" MV command is used to prepare reading of the match string.
The actual read operation is not performed with the "PHYSICAL WRITE" command.
● The memory area of the receive data of the "PHYSICAL WRITE" command only contains
the command identifier itself.
● Send the "Read match string" command with the "PHYSICAL WRITE" command and wait
for the positive response. Then read out the actual string with a "PHYSICAL READ"
command.
● The "PHYSICAL WRITE" command must specify the length "0x01"
("CMD_STRUCT.Length = 0x01"); otherwise, the command receives a negative
acknowledgment.
Table 9- 16
Parameter
CMD
OffsetBuffer
UID
Length
StartAddress
Table 9- 17
Address
0x0000
DISA bit
Command: Set DISA bit
The command data to be "written" in the "PHYSICAL WRITE" command only contains the
command identifier "Set DISA bit".
If the "DISA" bit of the optical reader has been set, the command receives positive
acknowledgment. If the "DISA" bit has already been set, it remains set.
The "PHYSICAL WRITE" command must specify the length "0x01"
("CMD_STRUCT.LEN_DATA = 0x01"); otherwise, the command receives a negative
acknowledgment.
116
CMD_STRUCT
Value
0x71
0x00
0x00
0x01
0x00
Memory area of the receive data (TXREF or RXREF)
Value
0x04
Meaning
Command identifier
"Read match string"
Operating Instructions, 05/2019, C79000-G8976-C494-02
SIMATIC MV500