Creating a Modbus Frame
To enhance performance, you can map several variables to
the same frame.
In the Modbus protocol, the data exchange is described by frames. A frame is a request to read an array of consecutive variables. Several frames can be necessary to access all the variables of a device. To enhance performance, reduce the number of frames by mapping several variables to the same frame.
- Click New frame, a new line with
default settings appears.
Item Name Description Options
A Function code Specifies the types of read requests that the energy server can perform. - FC01: coils (array of output or internal bits)
- FC02: discrete input (array of input bit)
- FC03: holding registers (array of output or 16-bit internal registers)
- FC04: input registers (array of 16-bit input registers)
B Starting address Specifies the address. 0–65535(1) C Item count Specifies the number of items that the frame contains. - 1–1000 for function code FC01 or FC02
- 1–125 for function code FC03 or FC04
D Number Specifies the type of information that is mapped on this frame. - Boolean for FC01 or FC02 function code
- Boolean or number for FC03 or FC04 function code
E Edit frame Describes the variables of this frame. – (1)There is an offset between register number and address. Register numbers can be found in the device documentation.
- When you finish adding and configuring frame settings, click Save changes.