Rockwell Automation 1760-xxxx Pico GFX-70 Controllers User Manual - Manual (Page 357)

Publication 1760-UM002B-EN-P - March 2005
Inside Pico GFX-70 8-3
Example:
screen size 250 bytes:
The loading time for the screen is: 250 x 80 µs = 20 ms
The loading of screen data and screen changes can be implemented in any
segment of the program cycle. Take this behavior into account when
considering the reaction time of your entire control system.
Effects on the Creation of the Circuit Diagram
Pico GFX-70 evaluates the circuit diagram in these six segments in succession.
You should take into account two factors when creating your circuit diagram.
• The changeover of a relay coil does not change the switching state of an
associated contact until the next cycle starts.
• Always wire forward or from top to bottom. Never work backwards.
Example: Self-Latching with Own Contact
Start condition:
Inputs I1 and I2 are switched on.
Q1 is switched off.
This is the circuit diagram of a self-latching circuit. If I1 and I2 are closed, the
switching state of relay coil [
Q 01
is “latched” via contact
Q 01
.
• 1st cycle: Inputs I1 and I2 are switched on. Coil Q1 picks up.
• Contact
Q 01
remains switched off since Pico GFX-70 evaluates from
left to right. The first coil field was already passed when Pico GFX-70
refreshes the output image in the 6th segment.
• 2nd cycle: The self-latching now becomes active. Pico GFX-70 has
transferred the coil states at the end of the first cycle to contact
Q 01
.
IMPORTANT
If you require the GFX to have a small cycle time:
use several small screens so that the loading time is not too
long during a screen change. Only display necessary
information in the screens concerned.
I 01-- | -I 02-..--[ Q 01
Q 01-- |