Rockwell Automation 1771-DB BASIC MODULE - Manual (Page 193)

Chapter
Call Routines 0–68 12
12 -3
Use this routine to receive data from the PLC processor. CALL 3 transfers
the block-transfer-write (BTW) buffer to the auxiliary processor on the
BASIC module for use in the next BTW request from the PLC processor.
If a data transfer does not occur within 2 seconds the routine returns to
your BASIC program with no new data. BASIC execution halts until the
BTW occurs or the call times out.
Whenever this call is active bit 1 (the sync BTW bit) of the PLC input
image table is set. You can use this bit to trigger a BTR rung. If you are
using CALLs 33, 34, 49, 50, 118, 122, or 123 you must use these bits to
perform synchronous block transfers. Synchronous block transfer is only
supported in PLC-5 processors. Only use the sync BTW bit with a PLC-5
processors.
Input and Output Arguments
This routine has no input arguments and one output argument. The output
argument is the status of the transfer.
0 = a successful transfer
92 (5CH) = mismatch in block transfer length between the BASIC
module and the block-transfer-write instruction.
94 (5EH) = call timed out before a successful block transfer completed
Syntax
CALL 3
POP status of transfer
Example
>10 CALL 3
>20 POP X
>30 IF X <> 0 PRINT “TRANSFER UNSUCCESSFUL”
CALL 3: Timed Block-
Transfer-Write Buffer