Kessler-Ellis Products INTELLECT-69PM2, Инструкция по установке и эксплуатации

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15
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SERIAL INTERFACE OPERATION:
Data is received and transmitted over standard EIA
RS232 or RS422 levels. Each ten bit character is
made up of a start bit, eight bit ASCII code and a
stop bit.
The input impedance of RS232 is 3K
Ω
to 7K
Ω
worst
case. The terminal addressing the unit must be
capable of driving all loads in the loop. The input
impedance of RS422 is much higher and there
should be no problem driving as many as 99 units.
The transmit line remains in a high impedance "off"
state until addressed. Only one unit is to be on line
at a time!!! More than one unit on line could damage
the unit or destroy the transmitted data.
When the unit is active (on line) it will operate in a full
duplex, echo back mode, so that data sent from the
terminal will be transmitted back for verification.
When the unit is "on line", use the proper serial
transmit commands to request data or set a new
value. If an error is made, a correction can be made
by back spacing and retyping correct data before
the return (enter) is sent. Once a return (enter) is
sent, the unit begins processing the data and will
transmit the requested data on a non-priority basis
over the data transmit line. The unit will not transmit
data if the Printer Busy line is activated (high).
When the Printer Busy line is activated all transmis-
sions are halted until the line goes low or open.
There should be a pause after data is requested to
insure that all data has been transmitted before
making another request or addressing another unit.
If transmission has not started within two seconds
after data is requested, it can be assumed that there
is a problem. The unit transmits a carriage return
and line feed after each data value. The unit will
stay "on line" until another unit is addressed.
RS232/RS422 - PC INTERFACE:
The following BASIC program is for setting up
RS232/RS422 on serial port (#1) at 300 baud. Run
this program after connecting the serial interface
connections.
10 SCREEN 0,0:WIDTH 80
20 CLS:CLOSE
30 OPEN "COM1:300,n,8,1,CS,DS,CD" AS #1
40 ON ERROR GOTO 110
50 B$=INKEY$
60 IF B$< >"" THEN PRINT #1,B$;
70 IF EOF (1) THEN 50
80 A$=INPUT$ (LOC(1),#1)
90 PRINT A$;
100 GOTO 50
110 RESUME