270
01700
01702
END(01)
Input sensor error processing program
Watchdog timer, RAM read/write, and
EEPROM error processing program
If IR 01700 is ON, check the connections to the
input sensor and cold junction compensator. If
connections are correct for both the input sen-
sor and cold junction compensator, replace the
Unit.
If IR 01702 is ON, turn power OFF and then
back on. If the error persists, replace the Unit.
Note If more than one error occurs at the same time, the error with the highest priority
will be output as the process value data.
Error priority from highest to lowest is as follows:
Watchdog timer > RAM read/write > EEPROM > Setting range > Input sensor
3-5-3 ON/OFF Control
The default value of the ON/OFF control hysteresis (i.e., SW1-1 is turned OFF)
of the Temperature Control Unit is 0.8 °C/°F. Refer to 3-6-1 Manual Settings (Ex-
pansion Mode) for details on changing the hysteresis.
The following table lists the effectiveness of hysteresis adjustment.
Adjustment Effect
Reduce the value • The hunting amplitude becomes small.
• When the process value is fluttering near the set point, the
output becomes unstable.
• The period between the output turned ON and turned OFF
becomes short.
Increase the value • The hunting amplitude becomes large.
• The output near the set point becomes stable.
• The period between the output turned ON and turned OFF
becomes long.
If ON/OFF control is used, in the following graph hunting, the amplitude and peri-
od of which depend on the controlled object, will occur even if the hysteresis of
Application Examples
Section 3-5
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