Omron CRT1 - 10-2008 Operation Manual page 451

Analog I/O Slave Unit Functions
Top/Valley Hold
Note
Setting Using the CX-Integrator
1,2,3...
428
Top/valley hold is used to hold the top and valley values of the analog input
value.
Analog values that fluctuate more than twice the hysteresis value are moni-
tored, and the top or valley values are held. The top or valley value is allo-
cated along with the Top/Valley Detection Timing Flags, which can be used to
check the hold timing.
When the Hold Flag (output) allocated in the OUT Area turns ON, the hold
function starts, refreshing the top or valley value until the Hold Flag turns OFF.
(The last value is held when the Hold Flag turns OFF, but the next time the
Hold Flag turns ON, the hold value is initialized as soon as a top or valley
occurs.) The comparator can be used to compare the top or valley value allo-
cated as analog data. (Refer to details on the comparator function.)
■ Example of Valley Hold
Hold value
Hold Flag
Hold function starts
Top/Valley Detection
Timing Flag
One-shot time
1. A delay in network transmission time will occur from the time the Hold Flag
turns ON (or OFF) in the Master Unit's ladder program until notification of
the flag's status is actually sent to the Slave. Therefore, even after the Hold
Flag is ON, the first analog data transmitted to the Master Unit after the
CPU Unit power is turned ON may be the data from when the Hold Flag
was OFF. To collect top/valley hold data using the Hold Flag at the Master
Unit, configure a ladder program which considers the transmission delay
time when the Hold Flag is turned ON, and enables only the top/valley hold
values after a fixed time lag.
2. The time that the Top/Valley Detection Timing Flags are ON can be adjust-
ed by setting the one-shot time. Use the CX-Integrator to set the one-shot
time (the setting range is 1 to 65,535 ms).
3. If the Hold Flag turns OFF during the time the Top/Valley Detection Timing
Flag is set to be ON, both flags will turn OFF simultaneously.
1. Turn ON the power supply to the CompoNet Slave Unit.
2. Double-click the icon of the Slave Unit to set in the Network Configuration
Window to open the Configuration Window. (Alternatively, right-click the
icon and select Parameters - Edit from the pop-up menu.)
3. Select the Tab Page for the input where top/valley hold is to be set, and se-
lect Top/Valley under the Function Choice heading.
Valley hold value
Analog input value
Section 11-4
Last value is held.
Hold function stops