The Modbus line provides the functions necessary to operate a Modbus TCP controller.
The following topics are covered in this section:
Modbus process objects
The following process objects are needed to access a Modbus variable:
Name |
Type |
Connection |
Usage |
Line |
"LNMODBUS" |
Modbus line. |
|
Device |
Device parameter |
Modbus communication device. |
|
Station |
Station parameters |
Modbus station (bus connector). |
|
Pvar |
Variable name |
Modbus variable. |
Allowed object structure for Modbus process objects:
Modbus access types
The following table shows an overview of all access types which are regulated via a line. All access types not listed here as well as access types to the PVI base object are executed by PVI Manager and therefore work independently of the line being used. The corresponding process object type is listed in the "Type" column.
Access types |
Type |
Special features |
Line |
Version of the line DLL. |
|
Line Device Station |
Lists all installed Modbus devices Lists all stations (bus controllers) specified in the configuration file Lists all process variables available in the configuration file for a station |
|
Variable |
Access to a variable's data. |
|
Variable |
Access to a variable's status. |
|
Variable |
Reads a variable's data type. |
|
|
Not supported |
|
|
Not supported |
|
|
Not supported |
|
|
Not supported |
|
|
Not supported |
|
|
Not supported |
|
|
Not supported |
|
|
Not supported |
|
|
Not supported |
|
|
Not supported |
|
Device |
Lists all defined stations. |
|
|
Not supported |
|
|
Not supported |
|
|
Not supported |
|
Station |
Lists all available process variables. |
|
|
Not supported |
|
Access type > 255 |
|
Not supported |
Modbus event types
The following table shows an overview of all event types which can be generated from a line. All event types which are not listed are generated by PVI Manager and therefore work independently of the line being used.
Event types |
Special features |
Not supported |
|
Not supported |
|
Event type > 255 |
Not supported |