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16ć21 – Rockwell Automation 1772-L8_LW_LWP_LX_LXP,D17726.5.8 User Manual User Manual

Page 232

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EAF

Process Control Instructions

Chapter 16

16-21

This list identifies the function of the ladder diagram symbols.

110/00 Manual Push Button
110/01 Auto Push Button
110/02 Enter Push Button
320/04 Set-Output bit
332 PID Set-Output value
115/00 Manual Override Output Value
340 PID CO Value

Figure 16.7 shows how you can cascade two loops by assigning the control
output (CO) of one loop as the set point (SP) of the next loop. Locate
these rungs in the main program. Set the cascade bit (word 01, bit 05) of
the inner loop so that it will interpret the outer loops properly.

Setting the cascade bit forces the set point of the secondary loop to accept
0 to 4095 binary. This allows the output of the primary loop to be moved
directly into the set point of the secondary loop.

Cascading Loops