Requan
Joined: 11 May 2008
Posts: 74
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| Rs232 timeout |
 Posted: Tue Jun 12, 2012 7:46 am |
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Dear All,
I wrote program for modbus communication, so i have two devices host and sensor.
Host send request and wait for answer from sensor. I did timeout in loop.
Strange thing is that when host first time(after restart) ask sensor i need put timeout more then 70000, from next time to forever 300 is enough.
Is this normal?
Functions:
| Code: |
#INT_RDA
void serial_isr() {
int t;
buffer[next_in]=getc();
t=next_in;
if(++next_in==BUFFER_SIZE)
next_in=0;
if(next_in==next_out) //get rid of the ';' here - wrong.....
next_in=t; // Buffer full !!
}
BYTE bgetc()
{
BYTE c;
while(!bkbhit) ;
c=buffer[next_out];
next_out=(next_out+1) % BUFFER_SIZE;
return(c);
}
int1 ModbusReceiveData(int16 BytesQuantity, int32 TimeOutValue,int8 SlaveID, int8 FunctionCode)
{
int1 Status = False;
int index=0;
BYTE temp_chr;
int32 TimeOutCounter = 0;
while (TimeOutCounter < TimeOutValue)
{
if (bkbhit)
{
TimeOutCounter = 0;
//Now have a character
temp_chr = bgetc(); //get the character
Modbus.BufferRs232[index]=temp_chr; //store the character
if (index<32) ++index; //and update the counter
if (index== BytesQuantity)
{
ModbusCalcCrc(BytesQuantity - 2);
if((Modbus.BufferRs232[index - 1] == Modbus.CRC_Hi) && (Modbus.BufferRs232[index - 2] == Modbus.CRC_Lo ))
{
if((Modbus.BufferRs232[0]==SlaveID)&&(Modbus.BufferRs232[1]==FunctionCode))// sprawdzam odebrany kod funkcji
{
Status = TRUE;
}
else
{
Status = FALSE;
}
}
else
{
Status = FALSE;
}
break;
}
}
TimeOutCounter++;
}
return Status;
}
void ModbusReadRegisters_Request(int8 SlaveID,int8 StartingAddress,int8 RegisterQuantity) //zapytanie na komende 03
{
output_high(TXEN);
Modbus.BufferRs232[0] = SlaveID;
Modbus.BufferRs232[1] = Modbus.Read_holding_register;
Modbus.BufferRs232[2] = 0;
Modbus.BufferRs232[3] = StartingAddress;
Modbus.BufferRs232[4] = 0;
Modbus.BufferRs232[5] = RegisterQuantity;
ModbusCalcCrc(6);
Modbus.BufferRs232[6] = Modbus.CRC_Lo;
Modbus.BufferRs232[7] = Modbus.CRC_Hi;
for(int i = 0;i < 8; i++)
{
putc(Modbus.BufferRs232[i]);
}
delay_ms(3);
output_low(TXEN);
}
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Main:
| Code: |
while(TRUE)
{
ModbusReadRegisters_Request(1,0x64,0x04); //01 03 00 64 00 04 05 D6
if (ModbusReceiveData(21,70000,1,3))
{
printf(lcd_putc,"\fT:%2.1fC H:%2.1f%%",Temp.ft,Humi.ft);
}
else
{
printf(lcd_putc,"\fError");
}
delay_ms(1000);
}
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