Rockwell Automation 1760-xxxx Pico Controller User Manual - Manual (Page 96)

Publication 1760-UM001D-EN-P - September 2005
4-36 Draw a Circuit Diagram with Pico
00000 is reached, this value is retained until the count direction is
changed.
Compatibility between Pico Series A Controllers and Pico Series B Controllers
High Speed Counters Pico provides various high-speed counter functions. These counter
function blocks are coupled directly to digital inputs. The following
functions are possible:
• Frequency counters: C15 and C16
• High-speed counters: C13 and C14
Frequency Counters
Pico provides two frequency counters, C15 and C16, for use as
required. The frequency counters can be used for measuring
frequencies. The high-speed frequency counters are permanently
connected to the digital inputs I3 and I4.
Frequency counters C15 and C16 can be used for determining motor
speeds, volume measurement using volume meters or the running of
a motor.
The frequency counter allows you to enter an upper threshold value
as a comparison value. The C15 and C16 frequency counters are not
dependent on the cycle time.
Counter Frequency and Pulse Shape
The maximum counter frequency is 1 kHz and the minimum counter
frequency is 4 Hz. The signals must be square waves with a
mark-to-space ratio of 1:1. If this is not the case, then the minimum
mark-to-space ratio is 0.5 ms.
DIR
CNT
RES
C1
+
{
0230
{
0000
{
C1 N +
AAAAA S
AAAA = S AAAAA
C1 = C1
+ = +
t
min
0.5
1
f
max
---------
×
=
t
min
= minimum time of the pulse or pause duration
f
max
= maximum count frequency (1 kHz)