Rockwell Automation 1771-DMC_DMC1_DMC4_DXPS Control Coprocessor User Manual - Manual (Page 121)

Chapter 7
Using the Serial Ports
7-13
/**************************************************************************
* The sg_parity is a bitfield of 8 bits.
* Bits 0 and 1, indicate parity. 00 = no parity
* 01 = odd parity
* 11 = even parity
* Bits 2 and 3, indicate bits/character. 00 = 8 bits/char
* 01 = 7 bits/char
* 10 = 6 bits/char
* 11 = 5 bits/char
* Bits 4 and 5, indicate stop bits. 00 = 1 stop bit
* 01 = 1 1/2 stop bits
* 10 = 2 stop bits
* Bits 6 and 7 are reserved.
* The sg_baud is the baud rate variable (one byte field).
* 0 = 50 baud 6 = 600 baud C = 4800 baud
* 1 = 75 baud 7 = 1200 baud D = 7200 baud
* 2 = 110 baud 8 = 1800 baud E = 9600 baud
* 3 = 134.5 baud 9 = 2000 baud F = 19200 baud
* 4 = 150 baud A = 2400 baud 10 = 38400 baud
* 5 = 300 baud B = 3600 baud FF = external
***************************************************************************/
/*** Set the options ***/
if ((status = _ss_opt(path, &opts)) == -1)
{
fprintf(stderr, “**** ERROR on setting port options! ***\n”);
return(-1);
}
/*** Make sure transmitter is off ***/
if ((status = _ss_enrts(path)) == -1)
{
fprintf(stderr, “**** ERROR on disabling transmitter! ***\n”);
return(-1);
}
/*** Make sure buffer is empty ***/
if ((size = _gs_rdy(path)) != -1) /* Is it empty? */
{
while (size--)
if ((status = read(path, &buff, 1)) == -1) /* Clear it out */
{
fprintf(stderr, “**** ERROR reading input buffer! ***\n”);
return(-1);
}
}
return(0); /* Everything ok */
} /* End of function */
/*****************************************************************************
* r e a d _ 4 8 5 . c
* PURPOSE: Read characters from a serial port configured for RS-485.
* REVISION LOG: 4/12/94 Original release of program
* USAGE: This function reads characters from a port configured for RS-485.
* Because RS-485 reads are no different than a normal read()
* function, this read_485 function merely makes a normal read()
* call. This function is only included to pair with the write_485()
* function. The write_485() function is quite different than a
* normal write() function.
* Function returns the number of bytes actually read. A -1 is
* returned if an error occurs. The error code is placed in the
* variable ’errno’.