Successful Block Transfer Read/Write - Allen-Bradley 1747-SN User Manual

Control Flag
EN
TO
Status Flag

EW

ST
ER
DN

Successful Block Transfer Read/Write

This example illustrates a successful BT operation.
The SLC control program fills in the M0 BT output/control buffer
and sets the enable (EN) flag.
 The scanner detects that the EN flag is set, validates the control
information, puts the BT request on the RIO link successfully,
and since no other BTs are pending for the same logical rack, sets
the enable waiting (EW) and start (ST) flag in M1 status field.
 The scanner receives a BT reply (with no errors) from the RIO
link device, fills in any requested BTR data, and sets the done
(DN) flag.
 The SLC control program detects the DN flag, processes the BT
data, and clears the enable (EN) flag.
 The scanner detects that the SLC control program has completed
processing (because the EN flag is clear) and clears the EW, ST
and DN flags. At this point the SLC control program could
initiate another BT operation in the same M0 BT buffer by setting
the EN flag.
RIO Block Transfer
Successful Block Transfer
M0 Control Information
M1 Status Information
5–15



 
Publication 1747 6.6 - July 1996