Industrial Automation
Industrial Automation | Europe


Main > Product Type > Software > Programming
Minimize Text   Default    Enlarge Text


CJ2M-MD211/MD212 Function Block For Read Actual Position(REAL)


This article provides details for the use and application of the Present Position Read (REAL) function block. Using this function block with the CJ2M-MD21/MD212 provides an easy means of reading the present position of a servo.

This function block can be of particular use in PLC-based motion control applications often found in packaging machinery. To see a machine case study of a packaging application that controls servos with the CJ2-Series Pulse Output Unit, visit the link below at the packaging solutions area.

Present Position Read (REAL)
Name Present Position Read(REAL): MD_CPU204_ReadActualPosition_REAL
Basic Function Reads the present position of the specified axis.
Originates from Tsunagi Lab Europe
Created by OEE-HQ HvB (creation and testing)
File Name MD_CPU204_ReadActualPosition_REAL.cxf
Applicable models CPU Unit CJ2M-CPU Unit version 2.0 or higher with max. two
CJ2M-MD211 (NPN) or
CJ2M-MD212 (PNP)
CX-Programmer Version 9.1.2 or higher
Conditions for usage None.
Function Description Reads the status of the output specified with the Axis No. (Axis) continuously as long as the Output enabled (Enable) is ON. When the Output enabled (Enable) is turned OFF, the Present position (Position) will be cleared to 0.
The Present position read completed (Done) is turned ON while valid present position is being read and output.
The Error flag (Error) will be turned ON and the Error code (ErrorID) will be output if an error occurs for this FB.
Strictly speaking, they are respectively turned ON or output only when Axis No. (Axis) is set out of range.
They are output by this FB, combining the states of the Status Bits in the Bit Area of the applicable CPU Unit.
These statuses, Present position read completed (Done)/ Error flag (Error)/ Error code (ErrorID), will be reset when Output enabled (Enable) turns OFF.

Kind of FB definition Connect Always ON type
  Connect the EN input to the Always ON Flag (P_ON).
  The same instance cannot be used in two or more places.
FB Precautions The MD_CPU* function blocks are offered 'as is' and may serve as a basis for development. Users should previously test its adequacy to the final application.

Omron can not be held responsible in case of malfunction.

EN input condition  • Connect the EN input to the Always ON Flag (P_ON).
 • If a different type of bit is connected to EN, the FB outputs will be maintained when the connected bit is turned OFF.
Application example Reads the present position of the pulse output 0 on the CJ2M-MD21* Unit when the Bit A is turned ON and outputs it to D0.

Related manuals  CJ2M Pulse I/O User Manual (W486)
 CJ2 Hardware User Manual (W472)
  • Variable Table 

Input Variables

Name Variable name Data type Default Range Description
EN EN BOOL     1 (ON): Starts FB
0 (OFF): Does not start FB
Axis No. Axis INT &0 &0 to &3 &0: Pulse output 0, &1: Pulse output 1
&2: Pulse output 2, &3: Pulse output 3
Enable output Enable BOOL 0(OFF)   1 (ON): Enables output
0 (OFF): Turns OFF output

Output Variables

Name Variable name Data type Range Description
ENO ENO BOOL   1 (ON): FB operating normally
0 (OFF): FB not operating normally
Present position read completed Done BOOL   Turns ON when present position read is completed normally.
Error flag Error BOOL   Turns ON when present position read is ended with an error.
Error code (May be omitted) ErrorID WORD   The error code of the error occurred in the FB will be output. For details of the errors, refer to the sections of the manual listed in the Related manuals above. When Unit No. or Axis. No. is out of the range, #0000 will be output.
Present position Position REAL -2.147484e+009 to +2.147484e+009 Outputs the present position of the specified pulse output.

Revision History

Version Date Contents
1.00 16-Feb-2012 Based on Function Block: _NCCPU204_ReadActualPosition_REAL


This manual is a reference that explains the function block functions. It does not explain the operational limitations of Units, components, or combinations of Units and components. Always read and understand the Operation Manuals for the system’s Units and other components before using them.



Comments (View All Comments / Add Comment)

Related Articles
No related articles found.
Created 2012-02-17
Modified 2014-03-13
Views 6355


You are not logged in.