Lakeshore Learning Materials 647 - Manual (Page 40)

Lake Shore Model 647 Magnet Power Supply User’s Manual
Remote Operation 4-10
Table 4-3 Sample BASIC Serial Interface Program
' SEREXAM.BAS EXAMPLE PROGRAM FOR SERIAL INTERFACE
' This program works with QuickBasic 4.0/4.5 or Qbasic on an IBM PC or compatible
' with a serial interface. It uses the COM1 communication port at 9600 BAUD. Enter
' an instrument command or query at the prompt. The command transmits to the
' instrument which displays any query response. Type "EXIT" to exit the program.
' NOTE: The INPUT instruction in this example accepts no commas as part of an input
' string. If a comma appears in an instrument command, replace it with a space.
'
CLS 'Clear screen
PRINT " SERIAL COMMUNICATION PROGRAM"
PRINT
TIMEOUT = 2000 'Read timeout (may need more)
BAUD$ = "9600"
TERM$ = CHR$(13) + CHR$(10) 'Terminators are <CR><LF>
OPEN "COM1:" + BAUD$ + ",N,8,1,RS" FOR RANDOM AS #1 LEN = 256
LOOP1: INPUT "ENTER COMMAND (or EXIT):"; CMD$ 'Get command from keyboard
CMD$ = UCASE$(CMD$) 'Change input to upper case
IF CMD$ = "EXIT" THEN CLOSE #1: END 'Get out on Exit
CMD$ = CMD$ + TERM$
PRINT #1, CMD$; 'Send command to instrument
IF INSTR(CMD$, "?") <> 0 THEN 'Test for query
RS$ = "" 'If query, read response
N = 0 'Clr return string and count
WHILE (N < TIMEOUT) AND (INSTR(RS$, TERM$) = 0) 'Wait for response
IN$ = INPUT$(LOC(1), #1) 'Get one character at a time
IF IN$ = "" THEN N = N + 1 ELSE N = 0 'Add 1 to timeout if no chr
RS$ = RS$ + IN$ 'Add next chr to string
WEND 'Get chrs until terminators
IF RS$ <> "" THEN 'See if return string is empty
RS$ = MID$(RS$, 1, (INSTR(RS$, TERM$) - 1)) 'Strip off terminators
PRINT "RESPONSE:"; RS$ 'Print response to query
ELSE
PRINT "NO RESPONSE" 'No response to query
END IF
END IF 'Get next command
GOTO LOOP1