Structure of Frames
- CIMON (Unlicensed)
Application Frame of CIMON PLC Ethernet Module
Application Data Format | |
Application Header Format | Application Instruction Format |
Master Frame Format (PC Party)
ID | Frame No. | Cmd | Res. | Length | Data | Check Sum |
Item | Size (Byte) | Description |
ID | 9 | Company ID |
Frame No. | 1 | Frame Number |
Cmd | 1 | Command |
Res. | 1 | Reserved Device |
Length | 2 | Length of Data Field |
Data | 1456 | Data Device |
Check Sum | 2 | Accuracy Check of Data |
ID
This is a 9-byte string like "KDT_PLC_M".
Frame No.
This, 1-byte data with the range from 0 to 127, is the number of the frame controlled by Master party. The start of this number can be any one within the range. But, when a new frame is sent, the number should be the value that ‘1’ is increased to the number given to the previous frame. If the frame of the same number is received in Slave party in the state that the response frame to the previous frame is not sent, the frame will be disregarded. If the response frame to the previous frame is sent and the frame of the same number is received, Slave party will respond normally.
Cmd
In Master, 1-byte command as the following table can be used and the format of ‘Data’ field is selected according to each command.
Cmd Code | Function | Remarks |
52h | Word Block Read | Reads data by the word. |
57h | Word Block Write | Writes data by the word. |
72h | Bit Block Read | Reads data by the bit. |
77h | Bit Block Write | Writes data by the bit. |
Res.
Reserved. (1 Byte, 00h) – Reserved device
Length
This is the 2-byte value indicating the size of ‘Data’ field. (Hexadecimal Figure)
Check-Sum
This is used to check the accuracy of data. After the data are received one by one and are summed, they are compared with the last coming check-sum to check whether an error occurs.
This is 2-byte value. After the entire frame is binary-summed by the byte, the lower 2-byte in the result value is used.
Slave Frame (Ethernet Module Party)
ID | Frame No. | Cmd | Res. | Length | Data | Check Sum |
ID
This is a 9-byte string like "KDT_PLC_S".
Frame No.
This is 1-byte data. The value that 128 are added to the number of the command frame received from the Master is used. As the Master receiving response frame expects the number of the response frame from the frame number used to command frame, it can be checked whether a frame is normal, using this Frame No.
Cmd
In Slave, 1-byte command as the following table can be used and the format of ‘Data’ field is selected according to each command.
Cmd Code | Function | Remarks |
52h | Word Block Data |
|
72h | Bit Block Data. |
|
41h | ACK Resp. |
|
Res.
Reserved. (1 Byte, 00h) – Reserved Device
Length
This is the 2-byte value indicating the size of ‘Data’ field. (Hexadecimal Figure)
Check-Sum
This is used to check the accuracy of data. After data are received one by one and are summed, they are compared with the last coming check-sum to check whether an error occurs.
This is 2-byte value. After the entire frame is binary-summed by the byte, the lower 2-byte in the result value is used.