IntroductionThis 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. industrial.omron.eu/vertical-flow-wrapper |
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| Name | Present Position Read(REAL): MD_CPU204_ReadActualPosition_REAL |
| Basic Function | Reads the present position of the specified axis. | ||
| Symbol |  |
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| 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) |
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| 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.
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| 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. |
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| 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. |
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| 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. |
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| 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.
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| Related manuals | CJ2M Pulse I/O User Manual (W486) CJ2 Hardware User Manual (W472) |
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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 |
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| 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 |
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| 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 |
Note
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.
