Ditel MICRA-D, Instruction Manual

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50 51
ISO 1745 PROTOCOL
The transmission format is: 1 START bit, 7 DATA bits, 1 EVEN PARITY bit and 1 STOP bit.
• MESSAGE FORMAT TO BE SENT
The message format, as sent from the master device, must consist of the following sequence of characters:
SOH D d STX C C X ...... X ETX BCC
One byte SOH of start of message [ASCII 01].
Two bytes corresponding the first to the tens and the second to the units of the instrument address number.
One byte STX of start of text [ASCII 02].
Two commands bytes according to the functions table.
In case of commands that change parameters, a block of N bytes corresponding to the new value including sign and decimal point.
One byte ETX of end of text [ASCII 03].
One control byte BCC calculated in the following manner:
Perform an exclusive-OR with all bytes between the STX (not included) and the ETX (included).
- If the obtained byte (in ASCII format) is higher than 32, it can be taken as the BCC.
- If the obtained byte (in ASCII format) is lower than 32, the BCC byte will be obtained by adding 32.
• MESSAGE FORMAT FROM INSTRUMENT
The format of a message as sent from the instrument in response to a command from the master device is the following:
2. In case of commands that ask for transmission of a value (data request type):
SOH D d STX X .................. X ETX BCC
One byte SOH of start of message [ASCII 01].
Two address bytes.
One byte STX of start of text [ASCII 02].
N bytes corresponding to the requested value (including the sign and decimal point).
One byte ETX of end of text [ASCII 03].
One control byte BCC calculated with the method described in above.
2. In case of commands that do not imply the return of a value (command type or changing parameter) :
D d ACK or D d NAK
The instrument sends a confirmation when it receives a message.
If the message has been correctly received and interpreted, the response will consist of two address bytes and one “ACK" [ASCII 06]
If the received message has not been well interpreted or it has been detected as to have errors, the response will be two address bytes and a "NAK"
[ASCII 21].
50 51
ISO 1745 PROTOCOL
The transmission format is: 1 START bit, 7 DATA bits, 1 EVEN PARITY bit and 1 STOP bit.
• MESSAGE FORMAT TO BE SENT
The message format, as sent from the master device, must consist of the following sequence of characters:
SOH D d STX C C X ...... X ETX BCC
One byte SOH of start of message [ASCII 01].
Two bytes corresponding the first to the tens and the second to the units of the instrument address number.
One byte STX of start of text [ASCII 02].
Two commands bytes according to the functions table.
In case of commands that change parameters, a block of N bytes corresponding to the new value including sign and decimal point.
One byte ETX of end of text [ASCII 03].
One control byte BCC calculated in the following manner:
Perform an exclusive-OR with all bytes between the STX (not included) and the ETX (included).
- If the obtained byte (in ASCII format) is higher than 32, it can be taken as the BCC.
- If the obtained byte (in ASCII format) is lower than 32, the BCC byte will be obtained by adding 32.
• MESSAGE FORMAT FROM INSTRUMENT
The format of a message as sent from the instrument in response to a command from the master device is the following:
1. In case of commands that ask for transmission of a value (data request type):
SOH D d STX X .................. X ETX BCC
One byte SOH of start of message [ASCII 01].
Two address bytes.
One byte STX of start of text [ASCII 02].
N bytes corresponding to the requested value (including the sign and decimal point).
One byte ETX of end of text [ASCII 03].
One control byte BCC calculated with the method described in above.
2. In case of commands that do not imply the return of a value (command type or changing parameter) :
D d ACK or D d NAK
The instrument sends a confirmation when it receives a message.
If the message has been correctly received and interpreted, the response will consist of two address bytes and one “ACK" [ASCII 06]
If the received message has not been well interpreted or it has been detected as to have errors, the response will be two address bytes and a "NAK"
[ASCII 21].