SYSTEM

Accesses the system parameters to enable performing these tasks:

Reading various cycle timing information and changing cycle timing

Resetting timing counters

Checking for and reading run-time errors

Backing up, saving, and restoring variables

Arguments
MODE	DINT	Identifies the system parameter and the access mode
ARG	DINT	New value for a "write" access
PARAM	DINT	Value of the accessed parameter

These are the available commands (pre-defined keywords) and expected arguments for the SYSTEM operator:

Command	Meaning	Argument	Value	Return Value
SYS_TALLOWED	reads allowed cycle timing	0	1	allowed cycle timing
SYS_TCURRENT	reads current cycle timing	0	2	current cycle timing
SYS_TMAXIMUM	reads maximum cycle timing	0	3	maximum detected timing
SYS_TOVERFLOW	reads cycle timings overflows	0	4	number of timing overflows
SYS_TWRITE	changes cycle timing	new allowed cycle timing	5	written time
SYS_TRESET	resets timing counters	0	6	0
SYS_ERR_TEST	checks for run time errors	0	16	0 if no error detected
SYS_ERR_READ	reads oldest run time error	0	17	oldest error code
SYS_INITBOO	backs up init Boolean	memory address	32	next free address
SYS_SAVBOO	saves Booleans	0	33	zero if OK
SYS_RESTBOO	restores Booleans	0	34	zero if OK
SYS_INITANA	backs up init analog	memory address	36	next free address
SYS_SAVANA	saves analogs	0	37	zero if OK
SYS_RESTANA	restores analogs	0	38	zero if OK
SYS_INITTMR	backs up init timer	memory address	40	next free address
SYS_SAVTMR	saves timers	0	41	zero if OK
SYS_RESTTMR	restores timers	0	42	zero if OK
SYS_INITALL	backs up init all types	memory address	44	next free address
SYS_SAVALL	saves all types	0	45	zero if OK
SYS_RESTALL	restores all types	0	46	zero if OK

Define the memory backup location using this syntax to back up variables for a specific type or for all types:

<new_address> := SYSTEM(SYS_INITxxx,<address>);

where:

<address>
is the memory backup address location (16# value for Hexadecimal format). The location must be an even address or the operation fails.

SYS_INITxxx
can be one of these:

SYS_INITBOO to define memory backup location for all Boolean variables.

SYS_INITANA to define memory backup location for all analog variables.

SYS_INITTMR to define memory backup location for all timer variables.

SYS_INITALL to define memory backup location for all Boolean, analog, and timer variables.

<new_address>
gets the next free address, for example, <address> + size of backed up variables (in bytes) according to SYS_INITxxx. This enables verifying the size of the required memory backup. If the operation fails, <new_address>
gets a zero value.

After having defined the backup memory location, perform backups of the variables at any time during the application. The backup is performed once only at the end of the current cycle. If the hardware delivers a Boolean input or a C function to inform of a power failure and allows at least one cycle delay before closing down, the backup may only be performed after detecting the power failure.

<error>
:=SYSTEM(SYS_SAVxxx,0
);

where:

SYS_SAVxxx can be one of these:

SYS_SAVBOO to ask for all Boolean variables backup.

SYS_SAVANA to ask for all analog variables backup.

SYS_SAVTMR to ask for all timer variables backup.

SYS_SAVALL to ask for all Boolean, analog and timer variables backup.

<error>
gets an error status other than zero when the operation fails (SYS_INITxxx is not called).

Restore variables at any time during the application. Perform the restoration once only at the end of the current cycle. Set an analog variable to a constant value for use as a signature to ensure the validity of the backed up data.

<error>
:= SYSTEM(SYS_RESTxxx,0
);

where:

SYS_RESTxxx
can be one of these:

SYS_RESTBOO to restore all Boolean variables.

SYS_RESTANA to restore all analog variables.

SYS_RESTTMR to restore all timer variables.

SYS_RESTALL to restore all Boolean, analog and timer variables.

<error
> gets an error status other than zero when the operation fails (SYS_INITxxx
is not performed).

Example

(* FBD example with "SYSTEM" operators *)

(* ST Equivalence: *)

alarm := (SYSTEM (SYS_TOVERFLOW, 0) <> 0);

If (alarm) Then

  nb_err := nb_err + 1;
  
  rc := SYSTEM (SYS_TRESET, 0);

End_If;

Operators

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