Lenze i550 - 12.13.3.1 Function Codes

12.13.3.1 Funcon codes
The inverter supports the following funcon codes:
Funcon code Funcon name Info
3 0x03 Read Holding Registers Reading of a single register or a group of several interconnected regis-
ters.
6 0x06 Preset Single Register Wring of a single register.
16 0x10 Preset Mulple Registers Wring of a single register or a group of several interconnected registers.
23 0x17 Read/Write 4X Registers Reading and wring within a transacon:
•
Wring of a data block into a group of several interconnected regis-
ters.
•
Reading from a block of interconnected registers.
Frame structure
Modbus Applicaon Header (MBAP) Protocol Data Unit (PDU)
Transacon
number
Protocol charac-
ters
(always 0x0000)
Number of the
bytes sll to fol-
low
Unit idener Funcon code Data / error code
2 bytes
2 bytes 2 bytes
1 byte 1 byte n byte
Tab. 1: ADU (Applicaon Data Unit)
Communicaon is established on the basis of the master/slave mode. Communicaon is
always started by a master request.
The inverter (slave) then either gives a valid response or outputs an error code (provided that
the request has been received and evaluated as valid message).
In case of a valid answer, the funcon code is returned. In the event of an error, a funcon
code assigned to the request is returned.
Error causes can be invalid CRC checksums, non-supported funcon codes or impermissible
data accesses.
Elements of the ADU:
•
MBAP (7 bytes)
•
Number of the bytes sll to follow in the message.
•
Address of the inverter.
•
The other bytes of the header are not described here.
•
Funcon code
•
The funcon codes exclusively refer to "4X registers", i. e. registers from the address
4000.
•
All data in the inverter can only be accessed via these 4X registers, see: Data map-
ping ^ 437
•
The 4xxxx reference is implicit, i. e. given by the funcon code used. In the frame there-
fore the leading 4 is omied in the addressing process.
•
Lenze supports the basic 1 addressing of Modbus, i.e. the numbering of the registers
starts with 1 whereas addressing starts with 0. For example, the address 0 is used in
the frame when register 40001 is read.
•
Data or error code
•
Checksum
All ADU contents are represented in the Big Endian format (most signicant byte rst).
Conguring the network
Modbus TCP
Data transfer
432