Default program
Many data logger settings can be changed remotely over a communications link. This convenience comes with the risk of inadvertently changing settings and disabling communications. For example, external cellular modems are often controlled by a switched 12 VDC (SW12V) terminal. SW12V is normally off; so, if the program controlling SW12V is disabled, such as by changing a setting or sending a new operating system, the cellular modem is switched off and the remote data logger will not turn it on. This could require an on-site visit to correct the problem unless a special program called default
has been installed.
Having a default.CR300
program stored on the data logger will also ensure that a non-compiling CRBasic program does not lock out a remote user.
The default program may use the extension .CR300,
.CRB
or .DLD
.
When a file named default.CR300
is stored on the data logger CPU: drive, it is loaded if no other program takes priority. Program execution priorities are as follows:
- When the CR300 series powers up, a program file marked as Run On Power-up will run. If that program includes a file specified by the Include File setting, it will be incorporated into the program that runs.
- If there is no program file marked Run Now or Run On Power-up (or if the program selected to run cannot be compiled), the data logger will run the program specified by the IncludeFile setting. For more information see IncludeFile.
- If the IncludeFile program cannot be compiled or if no program is specified, the data logger will attempt to run the program named
default.CR300
on its CPU: drive. - If there is no
default.CR300
file or it cannot be compiled, the CR300 series will not automatically run any program.
The default.CR300
program generally contains instructions to preserve critical datalogger settings such as communications settings, but should not be more than a few lines of code.
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Downloading operating systems over communications requires much of the available CR300 series memory. If the intent is to load operating systems via a communications link and have a default.CR300
file in the CR300 series, the default.CR300
program should not allocate significant memory, as might happen by allocating a large USR: drive. Also, do not auto-allocate tables in DataTable()
instructions; if it is necessary to use DataTable()
instructions, set small fixed table sizes. Refer to Sending an operating system to a remote data logger for information about sending the operating system.