Experimental Physics and
Industrial Control System

I think the stream device protocol converters %r and %<sum> will do what you want :

 

out “\x01\x01\x00\x01%4r%<sum>”;

 

But you would probably want to pass the address information as variables :

 

out $1 0x01 $2 $3 “%4r%<sum>”;

 

 

HI Tech-talk,I am trying to build an IOC to communicate with serial devices through the serial to Ethernet Device Server.

The serial device supports the streams of hex format.

The binary command format when using RS232 or RS485 is as follows:
Bytes    Meaning
1        Module address
1        Command number
1        Type number
1        Motor or Bank number
4        Value (MSB first!)
1        Checksum
total: 9 bytes

the checksum is calculated by adding up all bytes (including the module address byte) using
8-bit addition. Here is the examples to show how to do this:
    in C:
    unsigned char i, Checksum;
    unsigned char Command[9];

    //Set the “Command” array to the desired command
    Checksum = Command[0];
    for(i=1; i<8; i++)
        Checksum+=Command[i];
    Command[8]=Checksum; //insert checksum as last byte of the command
     //Now, send it to the module

I want to control the motor to rotate right  through the serial device.

Instruction:
Rotate right,   motor #1, velocity = 350
Binary:
Byte Index         0                1              2            3                  4               5                6                7               8
Function          Target-     Instruction   Type      Motor/         Operand     Operand      Operand     Operand      Checksum
                      address    Number                     Bank           Byte3        Byte2         Byte1          Byte0
Value (hex)        0x01       0x01          0x00       0x01            0x00         0x00            0x01           0x5e            0x62

By writing streamDevice protocol file(out'\x01\x01\x00\x01\x00\x00\x01\x5e\x62';),motor will rotate. Using "EDM" or "caput" to

input the variable,where do I do my processing (like calculating the Checksum and convert the velocity to four bytes long)? where

write my own parsing code in C?having other approaches. Could you give any example?

Thanks,

Yahto Dam
2010.11.16