Rockwell Automation 1771-QC , D17716.5.25 SER/B SERVO POS - Manual (Page 201)

Chapter 8
8Ć40
Rung 1
Rung 1 assures transfer of the parameter block at power up. This rung
examines the ready bits (WD050:0003/02 and WD050:00007/02) in the
status block. The parameter block address pointer (101) is stored in the
second word (102) of the parameter block. At power up, the parameter
block automatically transfers to the 1771-M3 controller. If the parameter
block is valid, the 1771-M3 controller turns on the ready bits
(WD050:0003/02) and WD050:0007/02) in the status block, thus
inhibiting rung 1.
Rung 2
If both axes are ready (bits WD050:0003/02 and WD050:0007/02 both
on), this rung moves the address pointer in the second word of the status
block (WD050:0102) to the control file addresses word (WB055:0004)
for the write-block-transfer instruction. The address pointer in the status
block contains the word offset for the parameter, command, or a moveset
block as requested by the 1771-M3 controller when the
write-block-transfer instruction is executed.
Rung 3
Rung 3 controls both the block-transfer read and the block-transfer write.
The examine-on instructions for the done bit (WB055:0000/15 and /05)
and the block-transfer-read request bit (WB055:0000/17) assures that the
read alternates with the write. The data file address for the block-transfer
read is always the address of the status block. The data file address of the
block-transfer write is controlled by rungs 1 and 2. The control file
address must always be in the binary section of the data table.
In addition to the rungs in Figure 8.17, you need a rung to clear the
block-transfer control word, as shown in Figure 8.10.
You also need rungs to perform the logic of rungs 5 thru 60, 64, and 65 in
Figure 8.16.
In this chapter, we told you about block-transfer instructions and
block-transfer timing. We also described programming examples.
However, you must not run an axis with your program until you first
follow the axis integration procedures we give you in chapter 9.
Summary