Eurotherm 346, Installation And Operation Manual

Page: 134 / 192

Section 5
Page 5 - 54 HA243821
Issue 5 Mar 98
MODEL 346 INSTALLATION AND OPERATION MANUAL
5.7.9 C PROGRAM LISTING (Cont.)
/**************************************************************************
FUNCTION : SEND ADDRESS
DESCRIPTION : This routine sends the EOT character followed by group and unit
addresses to “port”. It is assumed that addr contains GGUU in four
characters.
ARGUMENTS : port = port offset.
addr = pointer to address buffer.
RETURNS : Void
NOTES :
**************************************************************************/
void send_address( int port, char *addr )
{
int i;
send_byte(port,EOT);
for(i=0;i<4;i++)
send_byte( port, *addr++ );
}
/**************************************************************************
FUNCTION : SELECT CMD
DESCRIPTION : This routine selects the 34X instrument
ARGUMENTS : port = port offset.
addr = pointer to instrument address (GGUU)
cmd = pointer to command to be used
chan = pointer to channel character
reply = pointer to reply buffer
RETURNS : Should return ACK, but also NUL, ETX, EOT or NAK NOTES
**************************************************************************/
char select_cmd( int port, char *addr, char *cmd, char *chan, char *reply )
{
char bcc;
send_address(port,addr);
send_byte(port,STX);
send_byte(port,*chan);
bcc= *chan; /*Initialises BCC*/
bcc ^= *cmd; /*XORs with first character*/
while( *cmd != NUL )
{
send_byte( port, *cmd++ ); /*XOR with subsequent characters*/
bcc ^= *cmd;
}
bcc ^=ETX; /*XOR with ETX*/
send_byte(port,ETX); /*Send ETX*/
send_byte(port,bcc); /*Send BCC*/
return( get_reply( port, reply )); /* return ACK or NAK */
}