Carlo Gavazzi Controls S.p.A.
–
32100
–
Belluno
INFO: www.carlogavazzi-automation.com Phone +39.
0437 355811
User Manual
Modbus Master / SNMP Agent
Document code: SIU-SNM-01_ENG
Revision 1.0
2020-12-03
Page 23 / 25
Note: The data blocks from 1 to 8 are used to read/write the entire internal SNMP arrays of the
converter. The data are represented in bytes.
Each Modbus request defined in the section “Set Modbus Access” is associated to a specific OID too. In
order to read/write a specific Modbus request from SNMP, it is necessary to use the Data Block 9.
The Modbus request in write will be mapped consecutively to the Modbus request in read. So, in
the MIB structure, you will find all the Modbus request in read defined and then all the Modbus
request in write. See the following example for more information.
Example
:
We have defined two Modbus reading requests in the section “Set Modbus Access -> Modbus Read” and
two Modbus writing requests in the section “Set Modbus Access -> Modbus Write”.
In order to read the data related to the first Modbus reading re
quest (the first raw of the “Modbus Read”
table), the OID to require will be 1.3.6.1.4.1.33118.1.1.1.4.
9
.
1
where:
-
9
: Data Block 9
-
1
: First raw of the “Set Modbus Access” section
The Modbus request in write will be mapped consecutively to the Modbus request in read, so, in this
example, in order to write the first Modbus writing request
(the first raw of the “Modbus Write” table), the
OID to require will be 1.3.6.1.4.1.33118.1.1.1.5.
9
.
3
where:
-
9
: Data Block 9
-
3
: n + 1, where ‘n’ is the last raw number of the “Modbus Read” table.
Note: It is possible to read an entire data block or only a specific byte/value (for the Data Block 1
to 8). It depends on the OID used:
•
1.3.6.1.4.1.33118.1.1.1.4.x.0: entire data block
•
1.3.6.1.4.1.33118.1.1.1.4.x.y: value of the data block/specific byte
