On/Xoff Handshake - Roland DXY-1300 Command Reference Manual

5.3.3. X on/Xoff Handshake
In this handshake mode, the DXY-1000 outputs the character specified as an Xoff
character to the computer when the remaining buffer capacity is below a certain value. And
it also outputs the character specified as an Xon character to the computer when the re­
maining buffer capacity is above a certain value. The computer stops the data transmission
if an Xoff character is sent and starts the data transmission if an Xon character is sent.
This Xon character is specified by the ESC.I command and this Xoff character by the ESC.N
command. The remaining buffer capacity to output the Xon character is determined by the
ESC.I command The remaining buffer capacity to output an Xoff character is 512 bytes.
A sample program for the Xon/Xoff handshake and an explanation of how it works are
shown in Fig. 5-8
Sample program:
100 ' DXY-1000 RS-232C DEVICE CONTROL
110 ' SAMPLE PROGRAM FOR Xon/Xoff HANDSHAKE
120 OPEN "COM1:9600,N,8,1" AS #1
130 ON COM GOSUB 1000
140 PRINT #1,CHR$(27); . M0;0;0;13;0;0:";
150 PRINT #1,CHR$( 2 7 ) ; " . I 150;0;17: " ;
160 PRINT #1,CHR$(27);".N;19:";
170 PRINT,#1 ,CHR$(27);".@ ;0:";
180 COM ON
190 ' MAIN PROGRAM
END
1000 ' INTERRUPT Xon/Xoff
1010 IF LOC(1)=0 THEN RETURN
1020 A$=INPUT $(1,#1)
1030 IF A$=CHR$(19) THEN PRINT "Xoff
1040 PRINT "wait !!"
1050 A$=INPUT$(1,#1)
1060 IF A$=CHR$(17) THEN PRINT "Xon
1070 PRINT "ILLEGAL Xon !!"
1080 RETURN
Explanation:
Line 120 Opens the RS-232C port. Grammar varies depending on computers.
Line 140 Sets term inator for data output from the DXY- 1000 series to
[ ESC]CHR$(13).
Line 150 Taking the limit of the remaining buffer capacity as 150 bytes, sets Xon
character to IDC1]CHR$( 17).
Program for drawing
5-11
COMMAND
"
":COM ON:RETURN