DriveParamStrRead

Description

This function block reads a single drive parameter by sending an ASCII command to a drive. The value returned is the string response from the drive.

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• This differs from DriveParamRead in that the drive response is not parsed. DriveParamRead parses the drive response and returns the numeric value of the parameter and the units found that represent that parameter. Since DriveParamStrRead returns the drive response directly, it can be used to read parameters that have string representations, such as the AKD2G’s AXIS#.FAULTMSG# parameters.

See EtherCAT Function Blocks That Work With Drive Parameters for information about function blocks which work with drive parameters that are not supported by ML and MC function blocks.

Figure 7-188: DriveParamStrRead

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• This function block uses and reserves the EtherCAT SDO Channel. The SDO Channel will remain reserved until the done output is "true". Therefore, this FB should be called at each cycle until the done output is true. If it is not called at each cycle the rest of SDO communication (the AKD GUI "Graphical User Interface" A GUI is a type of user interface which allows people to interact with a computer and computer-controlled devices Views, for example) will be blocked.

  Using this FB in SFC "Sequential function chart" It can be used to program processes that can be split into steps. The main components of SFC are: - Steps with associated actions - Transitions with associated logic conditions - Directed links between steps and transitions P0 or P1 steps is not recommended as these steps are executed only once. If this FB is used in P0 or P1 then it must be used in an SFC N step to ensure the FB completes.

Arguments

Input

Execute	Description	Executes the Function Block A function block groups an algorithm and a set of private data. It has inputs and outputs.
	Data type	BOOL
	Range	0, 1
	Unit	N/A
	Default	—
Drive	Description	The address of the drive from which data is read.
	Data type	INT
	Range	—
	Unit	N/A
	Default	—
Param	Description	The parameter to read.
	Data type	STRING
	Range	—
	Unit	N/A
	Default	—

Output

Done	Description	Indicates whether this function block has completed without error.
	Data type	BOOL
	Unit	N/A
Error	Description	Indicates whether this function block call has completed with error:
	Data type	BOOL
	Unit	N/A
ErrorID	Description	The DriveParamStrRead error result if Error is TRUE (see list of Error Codes in table below). Upon success, Error is set to zero.
	Data type	DINT
	Unit	N/A
Value	Description	The value of the drive parameter. Value is only set when the function block has successfully completed.
	Data type	STRING
	Unit	N/A

Usage

Use this FB to read drive parameters that are not supported by other function blocks. Examples would be motor temperature, drive bus voltage, Present drive limit settings, present regen loading, drive display, and fault history.

Related Functions

DriveParamRead, DriveParamWrite

Example

Structured Text

            (* Read AXIS1.FAULTMSG1 on first AKD2G Drive on EtherCAT network *)

(* The code continually calls the FB (without re-executing it) until the first execution is done, then reads the returned value from the drive and reset the FB *)
      
IF ReadFaultMsg Then
   Inst_DriveParamStrRead1(True, 1001, 'AXIS1.FAULTMSG1' );
End_If;

On Inst_DriveParamStrRead1 Do
   FaultMsg := Inst_DriveParamStrRead1.Value; (* Reads the returned value from the drive *)
   Inst_DriveParamStrRead1(False, 1001, 'AXIS1.FAULTMSG1');
   ReadFaultMsg := False; (* Reset the FB *)
End_DO;