Delta Electronics VFD-S manual Communication program of PC

Chapter 5 ParametersVFD-S Series

3.7 Communication program of PC:

The following is a simple example of how to write a communication program for Modbus ASCII mode on a PC in C language.

#include<stdio.h>

#include<dos.h>

#include<conio.h>

#include<process.h>

#define PORT 0x03F8 /* the address of COM1 */ /* the address offset value relative to COM1 */ #define THR 0x0000

#define RDR 0x0000 #define BRDL 0x0000 #define IER 0x0001 #define BRDH 0x0001 #define LCR 0x0003 #define MCR 0x0004 #define LSR 0x0005 #define MSR 0x0006 unsigned char rdat[60];

/* read 2 data from address 2102H of AC drive with address 1 */ unsigned char tdat[60]={':','0','1','0','3','2','1','0',’2', '0','0','0','2','D','7','\r','\n'};

void main(){int i;
outportb(PORT+MCR,0x08);	/* interrupt enable */
outportb(PORT+IER,0x01);	/* interrupt as data in */
outportb(PORT+LCR,(inportb(PORT+LCR) 0x80));
/* the BRDL/BRDH can be access as LCR.b7==1 */
outportb(PORT+BRDL,12);	/* set baudrate=9600, 12=115200/9600*/
outportb(PORT+BRDH,0x00);
outportb(PORT+LCR,0x06);	/* set protocol, <7,N,2>=06H, <7,E,1>=1AH, <7,O,1>=0AH,
<8,N,2>=07H, <8,E,1>=1BH, <8,O,1>=0BH		*/
for(i=0;i<=16;i++){
while(!(inportb(PORT+LSR) & 0x20)); /* wait until THR empty */
outportb(PORT+THR,tdat[i]);	/* send data to THR */	}
i=0;
while(!kbhit()){

if(inportb(PORT+LSR) & 0x01){ /* b0==1, read data ready */ rdat[i++]=inportb(PORT+RDR); /* read data form RDR */

} } }

5-74 Revision August 2008, SE09, SW V2.61