TANDELTA OQSExISG2, Руководство пользователя

Страница: 75 / 130

Page | 73
11 Interface Options
Note: Oil condition output in Loss Factor % can be converted to Tan Delta Number.
This can be converted to TDN using the following formula where T = TDN, L = Loss Factor %:
T = 900 - 20L
T emperature outputs in °C and can be converted to °F using the following formula:
T(°F) = T(°C) × 1.8 + 32
11.1 Tan Delta Communication Protocol
The command protocol and language for the Tan Delta serial communications uses a binary
command format communicating over a half-duplex RS485 interface. The serial configuration
must be set to 8 bits with no parity and one stop bit. The default baud-rate is 9600 bits per
second. The Tan Delta unit operates in a slave mode, with the serial device which controls the
communications (e.g. the monitoring computer) acting as master and issuing commands to
which the slave will reply. Tan Delta will not transmit any data except in response to a
command from the master and will expect no further commands until the last command has
been replied to.
Commands are multiple sequences of bytes which must be interpreted as a complete data
string before the correct action and response can be determined. Any command which is not
interpreted and verified will cause the command interpreter to reset back to its initial state,
and any interruption of communications of longer than 1s will cause the same result. The
master must therefore check for correct response in all cases and re-send any commands which
have been corrupted or misinterpreted.
Note that all hexadecimal bytes referred to here are physically sent on the RS485 bus as pair of
ASCII characters. Thus the wake-
up character “!”, which has an ASCII value of 0x21 is physically
sent as the pair of ASCII bytes “2”, “1” (hex 0x32, 0x31). Thi s provides further security as only
valid ASCII characters are recognised and simplifies monitoring and debugging of command