SRS Labs SR530, Lock-In Amplifier manual IBM PC, Microsoft C v3.0, via RS232, Program Example

Program Example 3:

IBM PC, Microsoft C v3.0, via RS232

Machine language routines to interface to the COM1: RS232 port are provided in the file RS232.OBJ found on the SR575 disk. These routines allow for simple interfacing to the SR530 at 19.2 kbaud from C programs.

#include <stdio.h>

To use these routines, the large model must be used. Compile with the /AL switch and link with RS232.OBJ.

Only two wires between the IBM PC's ASYNC port and the SR530 are needed (pins #2 & #3 of the RS232), but pins 5,6,8 and 20 should be connected together on the connector at the IBM end.

/*	Compile with >MSC program name/AL;
	link with RS232.OBJ (on	SR565 disk)
	RS232.OBJ defines:
	init ()
		Initializes COM1: to 19.2 kbaud
	txstr (str);	str must terminate with ′$′ char
	Char *str;
		Sends string str to COM1:
	rxstr (str);	str must be declared with 15 characters
		or more length.
		Fills str with string received from COM1:
	If an error occurs, your procedure nocom() is called.
	Nocom() must be a	C procedure in your program.
	Example program to read	the SR510 outputs and ramp the x6 analog
	Output using Microsoft C v3.0 (large model) and the COM1: port.
	Set all switches in SW2	to UP on SR530 for 19.2 kbaud.

The ramp on x6 can be watched by setting the SR530 display to D/A.

*/

main ()

{

char str1[20], str2[20], STR3[20]; float v1,V2,x;

init ();	/* init	COM1: port to 19.2 kbaud */
txstr (″w0$″);	/* set character interval to 0 */
x = 0;
while (1)
{
txstr (″q1$″);	/* read	channel 1 output */
rxstr (str1);	/* into	str1 */
sscanf (str1, ″%f″, &v1);		/* scan str1 for a float variable */

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