ABB AnalyzeIT ZMT Series Aanvullende gebruiksaanwijzing - Pagina 8

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8

COMMUNICATION

8.1

Communication Between Master and Slaves

The commands from the master are coded as single
characters as follows:
R
– 'Read' (read parameters)
M
– 'Multiple Read' (read a selection of parameters)
W
– 'Write' (write new parameter values).

8.1.1 Mnemonics

Each mnemonic for the ZMT Analyzer parameters comprises
two characters – see Section 8.7.
8.2 Command Format – Figs. 8.1 to 8.3
The protocol is based on ANSI-X3.28-1976-2.5-A4. Entries
are made directly from the host computer using the command
format shown in Figs. 8.1 to 8.3.
Start
Command
W
STX
W
6
Instrument
Identification
(1 to 99)
Start
Command
STX
R
Fig. 8.1 'Read' Command Format
Instrument
Identification
(1 to 99)
Start
Command
STX
M
Fig. 8.2 'Multiple Read' Command Format
Instrument
Parameter
Identification
Mnemonic
(1 to 99)
(Section 8.6)
Fig. 8.3 'Write' Command Format

8.2.1 Term Clarification for Command Format

Start – one ASCII control character (always 'STX') signifying
the start of transmission.
Command – one character, R, M or W – see Section 8.1.
Instrument Identification – two characters identifying the
ZMT Transmitter, 1 to 99.
Parameter –
two-character
Section 8.7.
Sign – one character:
'+'
parameter value is positive (optional)
'–'
parameter value is negative.
Data – usually up to six characters (including decimal point)
used to write a new parameter value.
Limiter – one character (always 'ETX') signifying the end of
data transmission.
Block Check Character (BCC) – one character, the
arithmetic sum of the complete message (excluding parity
bits), transmitted by the host computer for error detection –
see Appendix A3.
Mnemonic
(Section 8.6)
(optional)
Limiter
ETX
Mnemonic
(Section 8.6)
(optional)
Limiter
ETX
Sign
(optional for
'Write'
Data (up to 6 characters)
command)
mnemonic
selected
BCC
BCC
BCC
(optional)
Limiter
ETX
from