Rockwell Automation 1336T PLC Comm. Adapter, Series B, FRN 2.xx-3.xx - Manual (Page 60)

3–16
Publication 1336 FORCE–5.13 –– September, 1998
The first rung causes a Block Transfer Write (BTW) to the PLC
Communications Adapter Board when the user logic bit is true. No
data is available from the drive for the PLC to read when the drive is
ready to accept a BTW.
The second rung causes a Block Transfer Read (BTR) from the PLC
Communications Adapter Board when data is available from the
drive for the PLC to read. The BTR rung is not conditioned with any
user logic because a BTR should occur whenever data is available
for the PLC to read from the PLC Communications Adapter Board.
The third rung causes a counter to increment each time the block
transfer ERROR bit (I:020/14) goes true. You can use this bit to
detect problems with the link from the PLC controller to the
SCANport device.