Communication; Communication Between Master And Slaves; Mnemonics; Relay Logic Equation (Q1, Q2) - ABB COMMANDER 300 Operating Instructions Manual

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 C300 Controller
parameters comprises two characters – see
Section 8.6.
8.1.2 Relay Logic
Equation (Q1, Q2)
The alarm relay assignment is transmitted in
the format in which it is displayed.
✶
Note. The terminator is transmitted
as a '#', but appears on the display as '
6

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.

8.2.1 Term Clarification

for Command Format
– one ASCII control character (always
Start
'STX') signifying the start of transmission.
– one character, R, M or W – see
Command
Section 8.1.
Instrument Identification
identifying the C300 Controller, 01 to 99.
Parameter
selected from Section 8.6.
– one character:
Sign
'+' –
'–' –
W
'.
– usually up to six characters (including
Data
decimal point) used to write a new parameter
value. However, up to 12 characters may be
used if Alarm Relay Assignment is being
carried out, i.e. using mnemonics Q1 and
Q2.
– one character (always 'ETX')
Limiter
signifying the end of data transmission.
Block Check Character (BCC)
the arithmetic sum of the complete message
(excluding parity bits), transmitted by the
host computer for error detection – see
Appendix A3 on page 28.
– two characters
– two-character
parameter value is positive
(optional)
parameter value is negative.
– one character,
mnemonic