ABB RETA-02, User Manual

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Communication
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Exception codes
The RETA-02 supports the Modbus exception codes shown
below.
Table 10.Supported exception codes
Function codes
The RETA-02 supports the Modbus function codes shown below.
Table 11.Supported function codes
Exception
code Name Description
01 Illegal
function Unsupported command
02 Illegal data
address Address does not exist or is read/write-
protected
03 Illegal data
value Value is outside minimum and maximum
limits. Parameter is read-only
Function
code Name Description Modbus
class
03 Read holding
registers Reads the binary contents of the
holding registers (4X
references) in the slave. 0
06 Preset single
register Presets a value into a single
holding register (4X reference). 1
16 (10h) Preset
multiple
registers Presets values into a sequence
of holding registers (4X
references). 0
23 (17h) Read/Write
registers Performs a combination of one
read and one write operation in
a single Modbus transaction.
The function first reads a group
of 4XXXX registers and then
writes new contents to a another
group of 4XXXX registers. 2