Go to Parker.com
  • Sign in
Technologies
  • Aerospace
  • Climate Control
  • Electromechanical Group
  • Filtration
  • Fluid and Gas Handling
  • Hydraulics
  • IoT
  • Pneumatics
  • Process Control
  • Sealing and Shielding
Blogs Forums Knowledge Bases
Parker Community
Parker Community
  • Technologies
    • Aerospace
    • Climate Control
    • Electromechanical Group
    • Filtration
    • Fluid and Gas Handling
    • Hydraulics
    • IoT
    • Pneumatics
    • Process Control
    • Sealing and Shielding
    Blogs Forums Knowledge Bases
  • User
  • Site
  • Search
  • User
Home Technologies Electromechanical Group Electromechanical - Industrial Electromechanical Industrial Knowledge Base Why is the IEC PLC making the axis to move farther and faster than programmed?
Electromechanical - Industrial
  • Technologies
  • Electromechanical Group
  • Electromechanical - Industrial
  • More
  • Cancel
Electromechanical - Industrial
Electromechanical Industrial Knowledge Base Why is the IEC PLC making the axis to move farther and faster than programmed?
  • Electromechanical – Industrial Support Forum
  • Electromechanical Industrial Knowledge Base
  • Members
  • Sub Groups
  • More
  • Cancel
  • New
Electromechanical - Industrial requires membership for participation - click to join
  • Electromechanical Knowledge Base & Frequently Asked Questions
  • Motion and Machine Controllers-
    • ACR Controllers-
      • 7000+
      • ACROBasic Programming (IPA/7000/9000)+
      • 9000 (Legacy)+
      • IEC PLC (9600) (Legacy)-
        • Acrobasic commands for IEC PLC
        • ACRView 6.4.1 Runtime Error for 9600 and 9640
        • ACRView IEC Editor not Compatible with Win10
        • Converting ACR9600 Projects to ACR9000 Projects
        • General Function Block Behavior
        • How to add multiple outputs in ACR IEC PLC ladder programs
        • How to change the Task Type or Task Speed
        • How to change velocity on the fly
        • How to home to a limit in ACR96xx
        • How to Modify a ACR-View project (9600) AcroBasic only programs for Win10
        • How to run an AcroBasic program from IEC PLC
        • How to start the IEC PLC on controller power-up
        • How to use Direct Variable references in ACR IEC PLC
        • IEC Error Message: No valid license for the current hardware
        • Invert Motion Direction in IEC PLC
        • Is there a First Scan flag in the IEC PLC
        • PLCOpen State Machine
        • Set Compax3-EPL Current Limit
        • User Function Block : Excess Position Error Response
        • User Function Block : Moving Average
        • User Function Block : Rotary Axis Position
        • User Function Block: Read Actual Torque
        • User Function Block: Software Limits
        • Using arrays in IEC PLC
        • Using the IEC Debug Window and Watch Lists
        • Variable Declarations in IEC Languages
        • VIDEO: How to import function blocks into ACR IEC_PLC projects
        • What is a Moving Segment Error?
        • Why is the IEC PLC making the axis to move farther and faster than programmed?
      • PC Card Controllers (Discontinued)+
    • PAC120+
    • PAC340+
    • PAC320 (Discontinued)+
    • 6K (Discontinued)+
  • General Technology Information+
  • Virtual Engineer+
  • Visualization and Human Machine Interface (HMI)+
  • Servo Drives and Servo Drive/Controllers+
  • Stepper Drives and Stepper Drive/Controller+
  • AC/DC Industrial Drives+
  • Gearheads+
  • Servo Motors+
  • Step Motors+
  • Linear and Rotary Positioners+
  • Electric Cylinders+
  • T-Slot Aluminum Framing+
  • C3 + Xpress + ETH+
  • How can I stay updated on Parker electromechanical and drives product news?
  • Legacy (Discontinued)+
  • Other+
  • Memorandum: Information on EPA ban of Persistent bioaccumulative toxin (PBT)
Wiki Actions
  • Share
  • More
  • Cancel
Community Quick Links
  • Home
  • Technologies
    • Aerospace
      • Supplier Resource Center
    • Climate Control
    • Electromechanical Group
      • Electromechanical - Industrial
      • Electromechanical – Mobile
    • Filtration
    • Fluid and Gas Handling
    • Hydraulics
    • IoT
      • Mobile IoT
    • Pneumatics
      • Pneumatic Industrial
      • Pneumatics Mobile
    • Process Control
    • Sealing and Shielding
  • Community Blogs
  • Community Forums
  • Community Knowledge Bases
Follow Us
  • Follow Parker Hannifin on social media

Follow Parker Hannifin on social media:

Why is the IEC PLC making the axis to move farther and faster than programmed?

Print Friendly and PDF

 Products: ACR9600, ACR9630, ACR9640

Several users have observed that while the IEC PLC was running, any command motion on the axes would result in approximately double the speed and distance commanded. This was occurring regardless of whether the motion was commanded using PLC Function Blocks, Acrobasic commands or using ACR-View tools like the Jog pendant. Halting the PLC programs would eliminate the "double move". In each case the problem was caused by improper use of direct variables.

In the ACR user guide, flags and parameters are marked as R (read only) and R/W (Read/Write). The controller and the PLC compiler do not actually restrict the user from writing to read-only variables. When designating a PLC direct variable as PW, the PLC will write a value to the variable every PLC scan. This can lead to undesired behavior when the controller is also trying to update the value internally.

An example of this problem is declaring position parameters are PW.

VAR
EPLDPOSITIONZ : DINT at %PW38176;(*reported EPL positon of Z axis*)
ENCODERy : DINT at %PW6160;(*ENCODER VALUE FOR Y AXIS*)
ACTUALX : DINT at %PW12290;(*Actual position of X axis in counts*)

END_VAR

Position parameters (such as actual position, encoder parameters and EPLD position) should NEVER be declared as PW (read/write).

Mar 2013-jw

  • Share
  • History
  • More
  • Cancel
  • Sign in to reply
Related
Follow Us
  • Follow Parker Hannifin on social media

Follow Parker Hannifin on social media:

Parker Hannifin Parker Hannifin

  • Products
  • About Parker
  • Investors
  • Community
  • Careers

Global Operations Global Operations

  • Divisions
  • Sales Companies
  • Worldwide Locations
  • Distribution Network
  • ParkerStore™ Network

Company Information Company Information

  • Newsroom
  • Event Calendar
  • Working with Parker
  • Product Brands
  • History

Global Support Center Global Support Center

  • Support
  • CAD
  • Where to Buy
  • Contact Parker
  • Manage Online Orders
© Parker Hannifin Corp 2023
  • Site Map
  • Safety
  • Privacy Policies
  • Terms and Conditions
  • Community Terms of Use
ENGINEERING YOUR SUCCESS.