Process interfacing via an automation system (PLC, PC)
9.3 Control with Ident profile
SIMATIC MV500
Operating Instructions, 06/2018, C79000-G8976-C494-01
121
Command: Read result string
Using the same mechanism as "Read trigger + result string", it is possible to read out the
decoded text of a code via CM.
Note that if "CM" was not selected as the trigger source in the WBM, the "PHYSICAL READ"
command will not trigger, it only returns the result of the decoding. If a result is already
available, this is returned. If there is not yet a result string available, the system waits until a
result string is available.
After processing of the command, the result string is available in the memory area of the
receive data specified in the command ("RXREF").
You can abort the execution of the command by setting the "INIT" bit.
Command: Read program number
When a "PHYSICAL READ" command is received, the MV command "Read program
number" ("PHYSICAL WRITE" command) must have been issued immediately beforehand in
order for the current program number to be returned. You can find more information on this
subject in the section ""PHYSICAL WRITE" commands / MV command interface
(Page 112)".
The "PHYSICAL READ" command must specify the start address "0x0000" and a length
"0x01" ("CMD_STRUCT.ADDR_TAG = 0", "CMD_STRUCT.LEN_DATA = 1").
The byte read at address "0x0000" contains the number of the program currently selected
and is stored in the memory area of the receive data after the command is processed.
Table 9- 27 CMD_STRUCT
OFFSETBUFFER 0x00
LEN_DATA 0x01
Table 9- 28 Command data area (TXREF or RXREF)
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