ABB AnalyzeIT ZMT Series, Дополнительные инструкции по эксплуатации

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2
The procedure is similar to that described in the Operating
Instructions (IM/ZMT) with additions as detailed in this section.
2.1 Company Standard Settings
Only those parameters detailed on the customer order are
programmed at the factory. If any parameters are unsuitable
for the application they can be reprogrammed – see Section 9
of the Operating Instructions (IM/ZMT). Serial data
programming procedures are detailed in Section 7 of this
manual.
Standard parameter settings for the serial data programme
are as follows:
Instrument Identity 01
Parity None
Block Check
Character (BCC)
BCC off
Transmission Rate 9600 baud.
Observe the limitations outlined in the Operating Instructions
(IM/ZMT). The maximum serial data transmission line length
for both RS422 and RS485 systems is 1200m.
The ZMT Series of oxygen analyzers is extended by the
addition of a serial data communication option which allows
addressing and reprogramming via a computer terminal or
host computer.
The RS422/485 communication standard is used with the
following logic levels:
a) for logic ‘1’ (MARK condition or IDLE state) the ‘A’ terminal
of the transmitter is negative (0V) with respect to the ‘B’
terminal (+5V)
b) for logic ‘0’ (SPACE condition or ACTIVE state) the ‘A’
terminal of the transmitter is positive (+5V) with respect to
the ‘B’ terminal (0V).
Note. ‘A’ terminal is Tx + or Rx + and ‘B’ terminal is
Tx – or Rx –.
Parity is used for simple error checking. The parity bit is a one-
bit code which is transmitted in addition to the ASCII character.
It can detect only one error per character, since two errors may
cancel out. Parity is calculated by finding the sum of logic ‘1’s
in the character and either:
a) setting the parity bit to logic ‘1’ if the sum is odd, or logic ‘0’
if the sum is even, when using even parity
or
b) setting the parity bit to logic ‘0’ if the sum is odd, or logic ‘1’
if the sum is even, when using odd parity.
The block check character (BCC) is an additional form of
checking and is the arithmetic sum of all the characters in a
complete message (excluding parity bits) – see Appendix A3.
Error detection is achieved by comparison of the BCC’s of the
transmitted and received messages.
This manual must be read in conjunction with the instrument
operating instructions detailed in IM/ZMT.
1 INTRODUCTION
2 PREPARATION