Siemens SIMATIC MV500, Operating Instructions Manual, Page: 162 / 294

Process interfacing via an automation system (PLC, PC)
9.3 Control with Ident profile
SIMATIC MV500
162
Operating Instructions, 03/2021, C79000-G8976-C494-05
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 CMD_STRUCT
Parameter Value
CMD 0x71
OffsetBuffer 0x00
UID 0x00
Length 0x01
StartAddress 0x00
Table 9- 17 Memory area of the receive data (TXREF or RXREF)
Address Value Meaning
0x0000 0x04 Command identifier
"Read match string"
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.
Table 9- 18 CMD_STRUCT
Parameter Value
CMD 0x71
OFFSETBUFFER 0x00
EPCID_UID 0x00
LEN_DATA 0x01
ADDR_TAG 0x00