Technical Information
MS40-S User Manual 211
The MESSAGE is a string with the following format:
<STX>+<ADDR>+<WIN>+<COM>+<DATA>+<ETX>+<CRC>
Where:
When a data is indicated between two quotes (‘...’) it means that the indicated data
is the corresponding ASCII character.
<STX> (Start of transmission) = 0x02
<ADDR> (Unit address) = 0x80 (for RS 232)
<ADDR> (Unit address) = 0x80 + device number (0 to 31) (for RS 485)
<WIN> (Window) = a string of 3 numeric character indicating the window
number (from ‘000’ to ‘999’); for the meaning of each window see the relevant
paragraph.
<COM> (Command) = 0x30 to read the window, 0x31 to write into the window
<DATA> = an alphanumeric ASCII string with the data to be written into the
window. In case of a reading command this field is not present.
The field length is variable according to the data type as per the following table:
‘-‘, ‘.’, ‘0’ . . . ‘9’ right justified with ‘0’
from blank to ‘_’ (ASCII)
<ETX> (End of transmission) = 0x03
<CRC> = XOR of all characters subsequent to <STX> and including the <ETX>
terminator. The value is hexadecimal coded and indicated by two ASCII
character.
The addressed SLAVE will respond with an ANSWER whose structure depends
from the MESSAGE type. When the MESSAGE is a reading command, the SLAVE
will respond transmitting a string with the same structure of the MESSAGE.
The controller can answer with the following response types:
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