Ulvac UTM300B, Инструкция по эксплуатации

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A-5
A3 SERIAL COMMUNICATIONS PROTOCOL
A3.3 Command to Answer Time-out: 1 sec.
Delays between COMMAND and ANSWER messages, longer that 1 sec., shall be considered
as a transmission line failure and special considerations should be made to re-send the
message.
The turbo molecular pump re-sends a COMMAND, if it does not receive and ANSWER within
a one second period.
A3.4 Command Transmission Specification
A command sent before an answer is sent, will be ignored by the turbo molecular pump, until
a reply to the first command is sent. However, this does not apply after a transmission time-out
occurs between command and answer. (If processing is performed normally, an answer is
returned within 100 msec.)
A3.5 Receiving Sequence
The character string from the turbo molecular pump unit is received after the COMMAND
character string is sent. When the carriage return code (0dH) is received, the received character
string is checked from the beginning and the portion from the initial command header "MJ" to the
carriage return code received last is processed as an answer.
Initialize the receive buffer after the answer character string is acquired from the receive buffer.
The read user memo (described below) may receive the same "MJ" as the command header
character string in the answer character string. Therefore, interpret the character string from the
first "MJ" appearing in the receive buffer to the carriage return as the answer character string.
A3.6 Using the Checksum Byte
Always calculate the checksum for a received character string and compare it with the
checksum byte data to confirm that the character string was received correctly. Conduct error
processing such as re-sending the command when a character string is received with an
incorrect checksum.
Calculation Example
In the received character string "MJ01LS97$" ($ represents the carriage return code), the
check sum code is represented by the last two characters : "97".
The checksum for the received character string is calculated as follows. The result shows that
the received character string is correct.
'M' 'J' '0' '1' 'L' 'S'
Checksum = 4dH + 4aH + 30H + 31H + 4cH + 53H = 197H =
97
H