Balluff BIS M-62 Series, Руководство пользователя

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BIS M-62_ MANUAL
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Page will be reset to zero (0x00), indicating that the host has received and processed its
pending data.
6.3.1 Modbus TCP - Host/BIS M-626_ Handshaking
When the host issues a command, it must first write the entire command to the Node Input
Page, leaving the Overall Length value to be written last.
For example, for the host to issue the 6-
word command “
Read Data
,” it must first write the
last five words of the command to Node Input Page 01, beginning at register 40002. After
which, the host will fill in the first word (at holding register 40001) with the Overall Length of
the command packet.
Last Five Words of a Read Data Command
Word MSB LSB Description
02 0xAA 0x05 Command ID: Read Data
03 0x00 0x01 Node ID: 0x01
04 0x03 0xE8 Timeout Value: 1 second
05 0x00 0x20 Read Start Address : 0x0020
06 0x00 0x04 Block Size : 4 Bytes
After writing the last five words of the command, the host will write the Overall Length value
to holding register 40001 of Node Input Page 01.
First Word of a Read Data Command
Word MSB LSB Description
01 0x00 0x06 Overall Length ( in words )
The moment the Overall Length value (at holding register 40001) of Node Input Page 01
changes from 0x0000 to a “non-zero” value, the BIS M-626_ will recognize the waiting data
and will execute the command.
6.3.2 Modbus TCP - Handshaking Example
1. The host or PLC issues an RFID command to the BIS M-626_, writing the command
string to the holding registers for Device ID 01 (Node Input Page 01). An Overall
Length value of 0x0006 is written last to holding register 40001.
2. The BIS M-626_ recognizes that the Overall Length value at holding register 40001
has changed for Device ID 01 (Node Input Page 01), indicating that a command is
waiting to be executed.
3. The BIS M-626_ executes the command and then clears the Overall Length holding
register of Device ID 01 (Node Input Page 01), setting it back the default value of zero
(0x0000).