Rockwell Automation 1760-xxxx Pico GFX-70 Controllers User Manual - Manual (Page 355)

1 Publication 1760-UM002B-EN-P - March 2005
Chapter
8
Inside Pico GFX-70
Pico GFX-70 Program Cycle In conventional control systems, a relay or contactor control processes all the
circuit connections in parallel. The speed with which a contactor switches is
thus dependent on the components used, and ranges from 15 to 40 ms for
relay pick-up and drop-out.
With Pico GFX-70 the circuit diagram is processed with a microprocessor that
simulates the contacts and relays of the circuit concerned and thus processes
all switching operations considerably faster. Depending on its size, the Pico
GFX-70 circuit diagram is processed cyclically every 0.1 to 40 ms.
During this time, Pico GFX-70 passes through six segments in succession.
How Pico GFX-70 Evaluates the Circuit Diagram
In the first four segments Pico GFX-70 evaluates the contact fields in
succession. Pico GFX-70 checks whether contacts are switched in parallel or
in series and saves the switching states of all contact fields.
In the fifth segment, Pico GFX-70 assigns the new switching states to all the
coils in one pass.
The sixth segment is located outside of the circuit diagram. Pico GFX-70 uses
this to: