Recovering From Sensor Not Connected Errors; Application Without A Cycle Refresh With The Cpu Unit - Omron CJ Series Operation Manual

Recovering from Sensor Not Connected Errors

4-2 Recovering from Sensor Not Connected Errors
4-3

Application without a Cycle Refresh with the CPU Unit

If a sensor is not connected for any loop, a sensor error will occur and the
ERC indicator on the front panel of the Unit will light. When necessary, the
control and alarm functions for any loop can be disabled. The following status
will result.
• The ERC indicator will not light to indicate sensor errors for the loop.
(Refer to ERC Indicator Lit and RUN Indicator Lit on page 73.)
• Control will not be performed for the loop.
• Alarms will not be given for the loop.
• Temperatures will not be input for the loop.
To disable both the control and alarm functions for one or more loops, set the
alarm modes 1 and 2 both to F Hex for each loop to be disabled in the Initial-
ization Data in the DM Area as shown in the following table.
DM Area
address
D (m)
D (m+1)
Example: Set bits 00 to 07 to FF Hex of D (m) to disable loop 2
Note The above settings are designed to be used to prevent the ERC indicator from
lighting as a result of a sensor error caused by not connecting a sensor for a
loop. If it is necessary to disable only the control function for a loop while leav-
ing the alarm function enabled, set the alarm modes for the loop and then turn
ON the Stop Bit for the same loop.
Cyclic refreshing of the Temperature Control can be disabled in the cyclic
refresh settings for Special I/O Units in the PLC Setup in the CPU Unit for the
following reasons:
• To shorten the CPU Unit cycle time
• To refresh Operation Data or Operating Parameters using interrupt tasks
or other processing from the ladder program in the CPU Unit.
If cyclic refreshing of Special I/O Units is disabled in the PLC Setup, refresh I/
O for the Unit at least once every 11 seconds using the I/O REFRESH instruc-
tion (IORF), being sure to take into consideration the increase in the cycle
time when IORF is executed.
If the I/O data for the Temperature Control Unit is not refreshed at least every
11 seconds, a CPU Unit monitor error will occur in the Temperature Control
Unit (the ERH and RUN indicators will be lit). Control from the Temperature
Control Unit will continue even if a CPU Unit monitor error occurs.
15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
Loop 1
Alarm mode 1 Alarm mode 2
Loop 3
Alarm mode 1 Alarm mode 2
Section 4-2
Bits
Loop 2
Alarm mode 1 Alarm mode 2
Loop 4
Alarm mode 1 Alarm mode 2
69