The Modbus holding register addresses for the Transparent profile are as with
the ABB Drives profile (see page 559).
Modbus function codes
The table below shows the Modbus function codes supported by the embedded
fieldbus interface.
DescriptionFunction nameCode
Reads the 0/1 status of coils (0X references).Read Coils01h
Reads the 0/1 status of discrete inputs (1X
references).
Read Discrete Inputs02h
Reads the binary contents of holding re-
gisters (4X references).
Read Holding Registers03h
Forces a single coil (0X reference) to 0 or 1.Write Single Coil05h
Writes a single holding register (4X refer-
ence).
Write Single Register06h
Provides a series of tests for checking the
communication, or for checking various intern-
al error conditions.
Diagnostics08h
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 Re-
gister
• 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 acknow-
ledge) 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.Get Comm Event Counter0Bh
Forces a sequence of coils (0X references) to
0 or 1.
Write Multiple Coils0Fh
Writes the contents of a contiguous block of
holding registers (4X references).
Write Multiple Registers10h
Modifies the contents of a 4X register using
a combination of an AND mask, an OR mask,
and the register's current contents.
Mask Write Register16h
Fieldbus control through the embedded fieldbus interface (EFB) 621
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