5 Implementation of Modbus TCP
5.5 Data width of the I/O-modules in the modbus-register area
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10/2011 MN05002008Z-EN
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5.5.2
Register 1130h: "Modbus-connection-mode"
This register defines the behavior of the Modbus connections:
5.5.3
Register 1131h: "Modbus-connection time-out"
This register defines after which time of inactivity a Modbus-connection is closed through a
Disconnect.
5.5.4
Register 0×113C and 0×113D: "Restore Modbus-connection parameter"
Registers 0×113C and 0×113D serve for resetting the parameter-register 0×1120 and 0×1130
to 0×113B to the default settings.
For this purpose, write "0×6C6F" in register 0×113C. To activate the reset of the registers,
write "0×6164" ("load") within 30 seconds in register 0×113D.
Both registers can also be written with one single request using the function codes FC16 and
FC23.
The service resets the parameters without saving them. This can be achieved by using a
following "save" service.
5.5.5
Register 0×113E and 0×113F: "Save Modbus-connection parameters"
Registers 0×113E and 0×113F are used for the non-volatile saving of parameters in registers
0×1120 and 0×1130 to 0×113B.
For this purpose, write "0×7361" in register 0×113E. To activate the saving of the registers,
write "0×7665" ("save") within 30 seconds in register 0×113F.
Both registers can also be written with one single request using the function codes FC16 and
FC23.
Table 14:
register 1130h:
Modbus-
Connection-
Mode
Bit
Name, description
15 to 2 reserved
1
MB_ImmediateWritePermission
– 0: With the first write access, a write authorization for the respective Modbus-
connection is requested. If this request fails, an exception response with excep-
tion-code 01h is generated. If the request is accepted, the write access is
executed and the write authorization remains active until the connection is
closed.
– 1:The write authorization for the respective Modbus-connection is already
opened during the establishment of the connection. The first Modbus-connection
thus receives the write authorization, all following connections don’t (only if bit 0
= 1).
0
MB_OnlyOneWritePermission
– 0: all Modbus-connections receive the write authorization
– 1: only one Modbus-connection can receive the write permission. A write permis-
sion is opened until a Disconnect. After the Disconnect the next connection
which requests a write access receives the write authorization.