Rockwell Automation 6008-SV2R VMEbus remote I/O Scanner - Manual (Page 147)

Chapter
Programming the Scanner
8
8Ć13
BT WRITE / BT READ
/*
**
** QUEUE_ONESHOT_BT() –– queue a one–shot block transfer read or write
**
**
This function is driven by the data contained in the bt_data structured provided by
** the caller. The command word (OSBTW/OSBTR), BT address word, tag word, and
** BT transfer length word are placed in the Control/Status Area. If the command is a
** OSBTW, then data is copied from the bt_data struct’s data buffer to the channel’s
** General Data Area. The command is then asserted and its results returned to
** the caller.
**
**
parameters: pointer to channel structure
** pointer to the bt_data structure
** return values: –1 = unable to lock general data area semaphore
** –2 = did not get cmd–complete interrupt
** ELSE channel confirmation status word
**
*/
int
queue_oneshot_bt (channel far *chan, bt_data far *block)
{
csa_data far *csa;
unsigned short far *gda;
unsigned short res;
unsigned short i;
/* map channel & establish pointers */
map_channel(chan);
csa = (csa_data far *) chan–>ControlStatusArea;
gda = (unsigned short far *) chan–>GeneralDataArea;
/* get the semaphore */
if (lock_gda(chan) != 0) {
unmap_channel(chan);
fprintf(stdout, ”osbtwrite: lock aquire FAILED\n”);
return –1;
}
/* set up the control/status area */
csa–>cnfstat = 0x000F;
/* confirmation status word */
csa–>cmd = block–>cmd; /* command word */
csa–>addr = block–>addr; /* address word */
csa–>tag = block–>tag; /* tag word */
csa–>datalen = block–>datalen; /* length of data word */
/* if a BT write */
if (block–>cmd == CMD_OSBTWRITE) {
/* copy the block data */
for (i = 0; i < block–>datalen; i++) {
gda[i] = block–>data[i];
}
}