Modbus Function Codes - ABB ACS850 Manual

Modbus function codes

Table below shows the Modbus function codes supported by the embedded fieldbus
interface.
Code Function name
0x03 Read Holding Registers
0x06 Write Single Register
0x08 Diagnostics
0x10 Write Multiple Registers
0x17 Read/Write Multiple
Registers
0x2B/0x0E Encapsulated Interface
Transport / Read Device
Identification
Control through the embedded fieldbus interface 337
Description
Reads the contents of a contiguous block of holding
registers in a server device.
Writes a single holding register in a server device.
Provides a series of tests for checking the
communication between the master and the slave
devices, or for checking various internal error
conditions within the slave. The following subcodes
are supported:
• 00 Return Query Data:
The data passed in the request data field is to be
returned in the response. The entire response
message should be identical to the request.
• 01 Restart Communications Option:
The serial line port of the slave device must be
initialized and restarted, and all of its communication
event counters cleared. If the port is in the Listen Only
mode, no response is returned. If the port is not in the
Listen Only mode, a normal response is returned
before the restart.
• 04 Force Listen Only Mode:
Forces the addressed slave device to the Listen Only
mode. This isolates it from the other devices on the
network, allowing them to continue communicating
without interruption from the addressed remote
device. No response is returned. The only function
that will be processed after this mode is entered is the
Restart Communications Option function (subcode
01).
Writes the contents of a contiguous block of holding
registers in a server device.
Writes the contents of a contiguous block of holding
registers in a server device, then reads the contents
of a contiguous block of holding registers (same or
different than those written) in a server device.
Allows reading of identification and other information
of the server.
Parameter "Read Device ID code" supports one
access type:
01: Request to get the basic device identification.
Returns ABB,ACS850.