User Manual

Motion control is easy
10.5 Motion control instructions
Easy Book
Manual, 03/2014, A5E02486774-AF
241
10.5.13
MC_ReadParam instruction (read parameters of a technology object) instruction
You use the MC_ReadParam instruction to read a select number of parameters that indicate
the current position, velocity, and so forth of the axis defined in the Axis input.
Table 10- 32 MC_ReadParam instruction
LAD / FBD
SCL
Description
"MC_ReadParam_DB"(
Enable:=_bool_in_,
Parameter:=_variant_in_,
Value:=_variant_in_out_,
Valid:=_bool_out_,
Busy:=_bool_out_,
Error:=_real_out_,
ErrorID:=_word_out_,
ErrorInfo:=_word_out_);
You use the MC_ReadParam
instruction to read single status
values, independent of the cycle
control point.
1
STEP 7 automatically creates the DB when you insert the instruction.
2
In the SCL example, "MC_ReadParam_DB " is the name of the instance DB.
The MC_ReadParam instruction works on an enable behavior. As long as the input "Enable"
is true the instruction reads the specified "Parameter" to the "Value" storage location.
The "MotionStatus" "Position" value updates at each Cycle Control Point (CCP) based upon
the current HSC value.
The "MotionStatus" "Velocity" value is the command velocity at the end of the current
segment (updated ~10ms). The MC_ReadParam can also read this value.
If an error occurs, the instruction switches to an error state that can only be reset by a new
rising edge at the input "Enable".
Table 10- 33 Parameters for the MC_ReadParam instruction
Parameter and type
Data type
Description
ENABLE
IN
Bool
Start the instruction. Default value: FALSE
PARAMETER
IN
Variant
Pointer to the TO-parameter that is to be read
VALID
OUT
Bool
If TRUE, the value has been read. Default value: FALSE
BUSY
OUT
Bool
If TRUE, the instruction is operating. Default value: FALSE
ERROR
OUT
Real
If TRUE, an error occurred. Default value: FALSE
ERRORID
OUT
Word
ID of the error. Default value: 0
ERRORINFO
OUT
Word
Related information to the ERRORID. Default value: 0
VALUE
INOUT
Variant
Pointer to the location where the read value is stored