7.1.29 Reporting reserved addresses
Considering RIO600 expansion, the Modbus point list depicts several addresses
reserved for future use. In the current implementation, if a 3X/4X read poll is made for
a Modbus address which is reserved for future use, the value “0” is reported to the
Modbus master. The Modbus master must be able to poll for a maximum number of
data points in one single poll and it should not return an exception in case a reserved
address region falls between two unreserved or currently assigned Modbus address
regions. However, during a write poll (4X), if a Modbus master is trying to write the
value to a Modbus address which is reserved for future use, an exception is returned
to the Modbus master.
Table 124: Correlation between the function code and address range
Module
name
Data type 0X 1X 3X 4X
Readable
(FC 01)
Writeable
(FC 05)
Readable
(FC 02)
Writeable Readable
(FC 04)
Writeable Readable
(FC 03)
Writeable
(FC 06)
DOM4 Boolean Yes Yes No No Yes No Yes Yes
DIM8H/
DIM8L
Boolean No No Yes No Yes No Yes No
RTD4 Signed 16
bit channel
status
informatio
n
No
No No No Yes No Yes No
Channel
range
informatio
n
(unsigned
16)
No
No No No Yes No Yes No
AOM4 Signed 16
bit channel
status
informatio
n
No
No No No Yes No Yes Yes
SIM8F/
SIM4F
Readable
data
Boolean
No
No Yes No Yes No Yes No
Writeable
data
Boolean
Yes
Yes No Yes No Yes Yes
Signed 32
bit Analog
data and
Signed 16
bit enum
No
No No No Yes No Yes No
SCM Boolean Yes Yes Yes No Yes No Yes Yes
SSR SSR1 and
SSR 2
unsigned
16 bit
informatio
n
No
No No No Yes No Yes No
Table continues on next page
Section 7 1MRS757488 H
Modbus TCP communication
182 RIO600
Installation and Commissioning Manual
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