Rockwell-automation 1771-QB Linear Pos. Manual de usuario descargar pdf (Pagina 160)

Sample Application Programs

Chapter 10

1016

Program Rungs for Application Program #2

Figure 10.15 and Figure 10.16 show the ladder diagram programming for this

application on a PLC-5/15 system. The rungs perform the following functions:

Rung 2:0

Rung 2:0 reads the module’s status block and, in conjunction with rung 2:5,

performs bidirectional block transfers to and from the module.

Important: Set the SQO length in rung 2:3 to the number of motion blocks to

be loaded, plus 1.

Rung 2:1

Rungs 2:1, 2:3 and 2:4 determine which block (parameter, motion or command)

will be sent to the module via the next block transfer write (BTW). If the axis 1

ready bit is low (the module is in powerup or a reset has just been executed),

rung 2:1 moves the source address of the parameter block into the BTW’s

control block, causing the programmable controller to send the parameter block

when rung 2:5 is executed.

Rung 2:2

When the ready bit first goes high (the module has just received a valid

parameter block), the control files for the sequencer output instructions (SQO)

are reset and a NOT instruction is performed on the status block word

containing the block transfer toggle bit (bit 7). The result is stored in reference

word B3:1 and guarantees that the data transition instruction (DTR) on rung 2:3

will be true, causing the first motion block to be loaded.

Rung 2:3

If the ready bit is high and the sequencer’s done bit is low (the module has

received a parameter block, but has not yet loaded all the motion blocks), the

data transition instruction (DTR) compares the block transfer toggle bit in the

status block with the state of the toggle bit from the previous scan. If they differ,

the next motion block’s address is sequenced into the BTW’s control block

causing the programmable controller to send the next motion block when rung

2:5 is executed.

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Rockwell-automation 1771-QB Linear Pos. Manual de usuario Pagina 160