Siemens SIMATIC MV500, Руководство по эксплуатации, Страница: 165 / 294

Process interfacing via an automation system (PLC, PC)
9.3 Control with Ident profile
SIMATIC MV500
Operating Instructions, 03/2021, C79000-G8976-C494-05
165
9.3.2.4 "PHYSICAL READ" commands
Supported MV commands
Using the "PHYSICAL READ" command, you can read out various MV commands (Machine
Vision commands).
The following commands are supported:
Table 9- 24 PHYSICAL-READ
CMD OFFSET
BUFFER
ADDR_
TAG
LEN_DATA RXREF
0x70 Offset in
the
"TXREF"
send buff-
er
0x0000 Length of the data to be fetched from
the reader:
Data fetched from the reader:
• ≥ code 2 • Trigger and result string
• = 01 • Program number
• ≥ match string 2 • Match string
Command: Trigger and read result string
To activate a trigger and read the result string, you will need to send a "READ" command with
address "0x0000". The table below shows the content of the memory area of the receive data
specified in the command ("CMD-STRUCT").
The total length of the result string is stored at the (virtual) addresses "0x0000" and "0x0001".
Note that if the result string is longer than the number of characters to be read
("CMD_STRUCT.LEN_DATA"), the end of the string is truncated. If the result string is shorter
than the number of characters to be read, the string is padded with the value "0x00".
You can also configure the format text so that the result bits "READ", "MATCH", "N_OK" are
inserted in the string.
If you do not want to know the total length of the result text, send a "PHYSICAL READ"
command starting at the address "0x0002" ("CMD_STRUCT.ADDR_TAG = 2").
You can also start to read from any start address, for example, when the result string is only
relevant starting at the 10th character in the code.
Table 9- 25 CMD_STRUCT
Parameter Value
CMD 0x70
OFFSETBUFFER 0x00
EPCID_UID 0x00
LEN_DATA ≥ length of the result string
ADDR_TAG 0x00