DriveParamRead

 Function Block - Reads a drive parameter by sending an ASCII command to a drive.

Inputs

Input	Data Type	Range	Unit	Default	Description
Execute	BOOL	FALSE, TRUE	N/A	No default	On the rising edge of Execute, a drive parameter is read. The function block processes only one request at a time. If Execute is toggled quickly so that another rising edge occurs before the function block has completed, the function block does not issue a second read command.
Drive	INT	-32768 to +32767	N/A	No default	The address of the drive where data is read. The first node usually has the value 1001. The second node usually has the value 1002. Use the members of the EtherCAT structure to specify a device's address to Create Variables.
Param	STRING	No range	N/A	No default	The parameter to read.

Outputs

Output	Data Type	Range	Unit	Description
Done	BOOL	FALSE, TRUE	N/A	Indicates whether this function block has completed without error.
Error	BOOL	FALSE, TRUE	N/A	Indicates whether this function block has completed with error.
ErrorID	DINT	No range	N/A	The DriveParamRead error result if Error is TRUE. See the EtherCAT Error Codes. Upon success, Error is set to 0 (zero).
Value	LREAL	No range	N/A	The value of the drive parameter. Value is only set when the function block has successfully completed.
Units	STRING	No range	N/A	The value of the drive parameter. Value is only set when the function block has successfully completed.

Remarks

• 
  

• This function block uses and reserves the EtherCAT SDO Channel.
  The SDO Channel remains reserved until the done output is TRUE.
  This FB should be called at each cycle until either the Done or Error output is TRUE.
  If it is not called at each cycle, the rest of SDO communication (e.g., the AKD GUI Views) is blocked.
  Using this FB in SFC P0 or P1 steps is not recommended because 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.

Usage

Use this function block to read drive parameters that are not supported by other function blocks.

Examples include:

• Drive bus voltage
• Drive display
• Fault history
• Motor temperature
• Present drive limit settings
• Present regeneration loading

• It takes multiple cycles to complete this function block.
• Typically only one DriveParamRead or DriveParamWrite function should be active for each axis at one time.
• If executing this function block continuously or if multiple times is required, add code that waits for this function block to complete (e.g., Done bit = 1) before executing it again.
  • See stats about the Execution Time.
• See EtherCAT Function Blocks that Work with Drive Parameters about function blocks not supported by ML and MC function blocks.

Figure 1: DriveParamRead

EtherCAT Error Codes

FBD Language Example

FFLD Language Example

IL Language Example

Not available.

ST Language Example

(* Read PL.KP on first AKD 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 ReadPropGain then
   Inst_DriveParamRead1( 1, 1001, 'PL.KP' );
End_If;

On Inst_DriveParamRead1.Done do
   Inst_DriveParamRead1( 0, 1001, 'PL.KP' );
   PositionProportionalGain := Inst_DriveParamRead1.Value; (* Reads the returned value from the drive *)
   ReadPropGain := 0; (* Reset the FB *)
End_DO;

See Also

DriveParamWrite