Siemens SENTRON PAC1020 - Modbus Measured Variables

Appendix
A.1 Modbus
PAC1020
80 Equipment Manual, 05/2020, L1V30610008B-01
A.1.2 Exception codes
Overview
Table A- 2 Modbus exception codes
Exception codes
Name
Meaning
Remedy
01
Illegal Function
Illegal function:
• The function code in the request is not a permis-
sible action for the slave.
• The slave is in a state in which it cannot process a
request of this type. This is the case, for example,
if it has not yet been configured and is requested
to return register values.
Check which function
codes are supported.
02
Illegal Data Ad-
dress
Illegal data address:
This address is not permissible for the slave. This is
the case, for example, if the combination of start
offset and transfer length is invalid.
Check the offset and the
number of registers.
03
Illegal Data Value
Illegal data value:
The request contains a data value that is not permis-
sible for the slave. This indicates an error in the re-
maining structure of a complex request, e.g. an
incorrect data length.
Check that the specified
offset and the specified
data length in the com-
mand are correct.
04
Slave Device Fail-
ure
Error in processing the data:
An indefinite error occurred when the slave attempt-
ed to execute the requested action.
Check that the specified
offset and the specified
data length in the com-
mand are correct.
A.1.3 Modbus measured variables with the function codes 0x03 and 0x04
Addressing the measured variables
You can use the Modbus function codes 0x03 and 0x04 on all the measured variables listed
below.
Note
Error in the case of inconsistent access to measured values
Please ensure the start offset of the register is correct for
read access operations.
Please ensure the start offset and the number of registers are correct for
write access
operations
.
If a value consists of two registers, a read command applied in the s
econd register, for
example, will generate an error code. The device will also output an error code if, for
example, a write operation ends in the middle of a multi-register value.