Toshiba IPE002Z Manual De Usuario
E6581741
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8. Modbus TCP server
8.1. Modbus TCP frames
Modbus TCP frames consist of a header and a Modbus request.
Header format:
Byte Description
Comments
0 high
order
1
Transaction
identifier
identifier
low order
2 high
order
3
Protocol
identifier
identifier
low order
This identifier always equals 0.
4 high
order
5
Length of data
low order
Number of bytes in the Modbus request +1. The frame length is
always less than 256 bytes, the value of the significant byte
therefore equals 0.
always less than 256 bytes, the value of the significant byte
therefore equals 0.
6
Destination identifier (Unit ID)
7 Modbus request function
code
The frame header returned by the VF-MB1/S15 server is identical to that of the frame
sent by the client.
8.2. Drive Modbus servers
The destination identifier (Unit ID) is used to access drive Modbus TCP servers:
Unit ID
Modbus TCP server
Accessible parameters
0-248
Variable speed drive
See the VF-MB1/VF-S15 instruction manual.
251 Option
board
255
IO Scanner
See the “IO Scanner” section.
8.3. List of Modbus functions supported
Function code
Modbus name
Description
Size of data
03
Read Holding Registers
Read N output words
63 words max.
06
Write Single Register
Write one output word
-
16 (0x10)
Write Multiple Registers
Write N output words
63 words max.
23 (0x17)
Read/Write Multiple Registers Read/write N words
(IO Scanning)
20/20 words max.
43 (0x2B)
Read Device Identification Identification
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