For function blocks that contain motion control instructions, the values of input parameters are
passed to the input variables when execution of the function block starts, and the values of the
output variables are passed to the output parameters when execution of the function block ends.
(Refer to Variable Designations for Function Blocks on page 6-11.) On the data trace displays,
input parameters and input variable, and output parameters and output variables, change in the
same task period.
* These numbers correspond to the data trace numbers 0 to 3.
Note You cannot use these system-defined variables in the user program. Use the GetTraceStatus instruction to
read the status of data tracing from the user program.
Differential monitoring reports the number of times the value of the specified BOOL variable matches
the specified condition. The specified condition is evaluated for a match in every task period of the pri-
mary periodic task (called the primary period). Differential monitoring provides a running total of the
number of times the condition is matched.
Related System-defined Variables
Variable name
Meaning Description Data type R/W
Member
_PLC_TraceSta[0..3]
*
_sTRACE_STA R
.IsStart Trace Busy Flag TRUE when a trace starts. BOOL R
.IsComplete Trace Completed
Flag
TRUE when a trace is completed.
Changes to FALSE when the next trace
starts.
BOOL R
.IsTrigger Trace Trigger
Monitor Flag
TRUE when the trigger condition is met.
Changes to FALSE when the next trace
starts.
BOOL R
.ParamErr Trace Parameter
Error Flag
Changes to TRUE when a trace starts if
there is an error in the trace settings.
FALSE when the settings are normal.
BOOL R
8-5-5 Differential Monitoring
The number of times the
value of the BOOL variable
changes is reported.
CPU Unit
Sysmac Studio