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Error Processing Section 7-7
then back to RUN again. Refer to Simple Communications Unit Control on
page 238 for details on the RUN/Stop Digit.
Note The Communications Control Area (Read and Write Command Bits) and the
CompoWay/F Read and Write Variable Type Areas are read every scan, so it
is not necessary to switch the Unit from Stop to RUN after these areas have
been edited.
Syntax Errors When a syntax error occurs in the Simple Communications Unit, switch the
Unit from RUN to Stop, correct the cause of the syntax error, and then switch
the Unit back to RUN.
Syntax errors are non-fatal errors that are cleared by switching the Unit from
Stop to RUN. Non-fatal errors are not cleared just by eliminating the cause of
the error.
DM Allocation Errors When a DM allocation error occurs, it is possible that the DM allocation
exceeds the boundary of the CPM2C’s DM Area. After correcting the DM allo-
cation, reset the power supply for the Simple Communications Unit.
DM allocation errors are fatal errors that are cleared by resetting the power
supply. Fatal errors are not cleared just by eliminating the cause of the error.
Delaying the
Communications
Response with
Components
The communications timeout setting must be extended if you are using a sys-
tem configuration that causes a significant delay in the communications
response between the Simple Communications Unit and the components,
such as wireless communications between the Unit and components. The
communications timeout setting can be set in multiples of 500 ms, up to the
maximum monitoring time of 5.0 s. Set a monitoring time appropriate for your
system.
Note 1. Under normal conditions, it is not necessary to change the communica-
tions timeout setting. In general use a setting of 0, which sets a response
monitoring time of 500 ms. Refer to Simple Communications Unit Control
on page 238 for details on the communications timeout setting.
2. There are restrictions on the number of times data can be written to the
Temperature Controller’s non-volatile memory. When frequently sending
data to a Temperature Controller, either set the Write Command Bit to 0 af-
ter writing is completed, or set the write mode for the Temperature Control-
ler to RAM write mode. Also, execute commands to select the RAM write
mode and backup mode in only one scan. Some devices will write to non-
volatile memory each time the modes are selected, and the life of the non-
volatile memory will be exhausted much more quickly if selections are
made every scan.
7-7 Error Processing
The Simple Communications Unit can detect two kinds of errors: fatal errors
cause the ERR indicator to light and non-fatal errors cause the ERR indicator
to flash. The following tables show the likely causes of these errors and the
error processing required.
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