Rockwell Automation 1760-xxxx Pico Controller User Manual - Manual (Page 94)

Publication 1760-UM001D-EN-P - September 2005
4-34 Draw a Circuit Diagram with Pico
You can wire up coils RC1 and DC1 as required. Select relay contact
C1, move the cursor to 1 and press Ok.
The parameter set for counter relay C1 is displayed.
Determine Counter Frequency
The maximum counter frequency depends on the length of the circuit
diagram in Pico. The number of contacts, coils and circuit connections
used determines the scan time (cycle time) required to process the
Pico circuit diagram.
To determine the scan time refer to Determine Cycle Time of Circuit
Diagrams on page 8-3.
The maximum counter frequency depends on the maximum scan
time.
Use the following formula to determine the maximum counter
frequency:
f
c
= maximum counter frequency
t
c
= maximum scan time
0.8 = correction factor
EXAMPLE
When using a Pico with only three circuit
connections for counting, resetting and outputting
the result via the output, the counter frequency may
be 100 Hz.
EXAMPLE
The maximum scan time is t
c
= 4000 µs (4 ms).
I1---------CC1
I3---------DC1
I2---------RC1
C 1 --------{Q1
0005
DIR
CNT
RES
{
{
C1
+
f
c
1
2 t
c
Ч
-------------- 0.8
Ч
=
f
c
1
2 4 ms
×
--------------------- 0.8 100 Hz =
Ч
=