Rockwell Automation 6008-SI IBM PC I/O SCNNR 6008-SI - Manual (Page 95)

Chapter 8
Block Transfer
8-5
bt_que
Use this routine to initiate a BT. This routine adds a BT to the pending list
and interrupts the scanner to pass it the command.
Calling sequence:
status = bt_que(
command, address, &packet
);
Arguments:
command: an integer, either C_BT_READ or C_BT_WRITE.
address:
an integer, the module or slot address (0–127), formed by
multiplying the rack address (0–7) by 16 and adding the slot address
(0–15). Equivalent arithmetic would be rack times 16, plus group times
2, plus 1 for right–hand slot or 0 for left–hand slots.
packet: a pointer to a QBT structure where you have filled in the
length of data (and the data, for a write BT).
Returned values:
error status, OK if the request was successfully entered in the queue or
NOT_OK if the queue was full or the request was invalid. This is the
status of queuing the request, not of executing it. Your program can
determine the latter status by examining the qbt_stat field in the packet.
Example:
static QBT btr;
#define CHANNEL_IN (16*2 + 3) /* slot 3, rack 2 */
. . .
btr.qbt_len = 15;
if ( bt_que(C_BT_READ, CHANNEL_IN, &btr) )
printf(“can’t queue the read BT\n”);