Omron DRT2 SERIES DEVICENET SLAVES - OPERATION MANUAL 04-2008 Operation Manual page 432

Temperature Input Terminals
Top/Valley Hold
Setting Using the DeviceNet Configurator
1,2,3...
Top/valley hold is used to hold the top and valley values of the temperature
input value.
Temperature values that fluctuate more than twice the hysteresis value are
monitored, and the top or valley values are held. The top or valley value is
allocated 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 temperature data 1. (Refer to details on the comparator function.)
Example of Valley Hold
Hold value
Hold Flag
Hold function
starts.
Top/Valley Detection
Timing Flag
Note 1. A delay in network transmission time will occur from the time the Hold Flag
turns ON (or OFF) in the Master's ladder program until notification of the
flag's status is actually sent to the Slave. Therefore, even when the Hold
Flag is ON, the first temperature data transmitted to the Master when 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,
configure a ladder program which considers the transmission delay time
when the Hold Flag is turned ON, then enables the top/valley hold values
after a fixed time interval.
2. The time that the Top/Valley Detection Timing Flags are ON can be adjust-
ed by setting the one-shot time. Use the Configurator 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. Double-click the icon of the Temperature Input Terminal to be set in the
Main Window and open the Edit Device Parameters Window. (From the
Maintenance Mode Window, click the right mouse button over the Slave
icon and select Parameters and Edit.)
Temperature
input value
One-shot time
Section 7-6
Valley hold
value
Last value
is held.
Hold function
stops.
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