Precise Instrument DAT 400, Техническое руководство

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SERIAL COMMUNICATION PROTOCOLS
CONTINUOUS, AUTOMATIC AND MANUAL TRANSMISSION PROTOCOL
These protocols have been programmed into their programming menu.
The string is transmitted as follows:
STX <status> <net weight> <gross weight> <peak> ETX <chksum> EOT
Where
STX (start of text) = 0x02h
ETX (end of text) = 0x03h
EOT (end of transmission) = 0x04.
<status> = an ASCII character that can take the following values:
“S” = stable weight.
“M” = weight that is not stable (moving).
“O” = weight greater than the maximum capacity.
“E” = weight that cannot be detected.
<net weight> = field consisting of 6 ASCII characters of net weight.
<gross weight> = field consisting of 6 ASCII characters of gross weight.
<peak> = field consisting of 6 ASCII characters of peak.
<chksum> = 2 ASCII control characters calculated considering the characters between STX and ETX
excluded. The control value is obtained by executing the operation of XOR (or exclusive) of the 8-bit
ASCII codes of the characters considered. The result is a character that is expressed in hexadecimal
with 2 digits that can take values from “0” to “9” and “A” to “F”.
<chksum> is the ASCII encoding of the two hexadecimal digits.
In the case of continuous communication protocol, the given string is transmitted at a frequency of 10
Hz, regardless of the weight filter selected.
In the case of automatic and manual communication protocols, between 2 weight transmissions, the
weight must have a variation corresponding at least 20 divisions.
SLAVE TRANSMISSION PROTOCOL
LIST OF THE CONTROLS AVAILABLE:
• Request for the net and gross weight and current peak.
• Change in gross weight.
• Change in net weight.
• Command of reset or automatic calibration or peak reset.
• Programming the two setpoints of weight
• Requesting the programmed setpoints.
• Control of setpoints storage in permanent memory.
The unit connected to the instrument (typically a personal computer) acts as a MASTER and is the only
unit that can start a process of communication.
The process of communication must be made by the transmission of a string by the MASTER, followed
by a reply from the SLAVE concerned.