Publication 1747-UM013B-EN-P - January 2005
Block Transfer Examples for Earlier Processors
D-27
Bidirectional Alternating Repeating Block Transfer
The following rungs demonstrate a bidirectional alternating repeating
block transfer. Using these rungs ensures the block transfer requests
are executed in the order in which they are sent to the queue. This
example also ensures that the BTR and BTW repeatedly alternate. The
XIO conditions prevent the BTR and BTW from queuing
simultaneously. The BT’s continue as long as the ladder rungs are
scanned.
Rung 2:0
CONFIGURE THE BT OPERATION TYPE, LENGTH AND RIO ADDRESS (R,G,S IN DECIMAL) AT
POWER-UP. BIT N7:50/7 MUST BE SET TO A ”1” TO INDICATE A BTR AND N7:53/7 MUST
BE A LOGICAL ”0” TO INDICATE A BTW OPERATION.
| |
| |
| |
| POWER-UP BTR |
| BIT CONTROL |
| S:1 +COP---------------+ |
|----] [----------------------------------------------+-+COPY FILE +-+-|
| 15 | |Source #N7:50| | |
| | |Dest #M0:1.100| | |
| | |Length 3| | |
| | +------------------+ | |
| | | |
| | | |
| | | |
| | BTW | |
| | OPERATION | |
| | +COP---------------+ | |
| +-+COPY FILE +-+ |
| |Source #N7:53| |
| |Dest #M0:1.200| |
| |Length 3| |
| +------------------+ |
Rung 2:1
COPY THE BTR STATUS AREA TO AN INTEGER FILE ONLY WHEN A BTR IS IN PROGRESS.
THIS STATUS DATA WILL THEN BE USED THROUGHOUT THE PROGRAM AND WILL LIMIT THE
NUMBER OF M-FILE ACCESSES
| |
| |
| |
| BTR |
| PENDING BTR STATUS |
| B3 +COP---------------+ |
|-+----] [-----+------------------------------------------+COPY FILE +-|
| | 0 | |Source #M1:1.100| |
| | | |Dest #N7:60| |
| | | |Length 4| |
| | | +------------------+ |
| | | |
| | | |
| | | |
| | CHECK BTR | |
| | STATUS | |
| | B3 | |
| +----] [-----+ |
| 2 |
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