Modbus Function Codes - ABB ACS560 Firmware Manual

Fieldbus control through the embedded fieldbus interface (EFB) 459

Modbus function codes

The table below shows the Modbus function codes supported by the embedded
fieldbus interface.
Code Function name
01h Read Coils
02h Read Discrete Inputs
03h Read Holding Registers
05h Write Single Coil
06h Write Single Register
08h Diagnostics
0Bh Get Comm Event
Counter
0Fh Write Multiple Coils
10h Write Multiple Registers
16h Mask Write Register
17h Read/Write Multiple
Registers
Description
Reads the 0/1 status of coils (0X references).
Reads the 0/1 status of discrete inputs (1X
references).
Reads the binary contents of holding registers (4X
references).
Forces a single coil (0X reference) to 0 or 1.
Writes a single holding register (4X reference).
Provides a series of tests for checking the
communication, or for checking various internal error
conditions.
Supported subcodes:
• 00h Return Query Data: Echo/loopback test.
• 01h Restart Comm Option: Restarts and initializes
the EFB, clears communications event counters.
• 04h Force Listen Only Mode
• 0Ah Clear Counters and Diagnostic Register
• 0Bh Return Bus Message Count
• 0Ch Return Bus Comm. Error Count
• 0Dh Return Bus Exception Error Count
• 0Eh Return Slave Message Count
• 0Fh Return Slave No Response Count
• 10h Return Slave NAK (negative acknowledge)
Count
• 11h Return Slave Busy Count
• 12h Return Bus Character Overrun Count
• 14h Clear Overrun Counter and Flag
Returns a status word and an event count.
Forces a sequence of coils (0X references) to 0 or 1.
Writes the contents of a contiguous block of holding
registers (4X references).
Modifies the contents of a 4X register using a
combination of an AND mask, an OR mask, and the
register's current contents.
Writes the contents of a contiguous block of 4X
registers, then reads the contents of another group of
registers (the same or different than those written) in
a server device.