Control Logix Rack

 

Are solenoid drivers still required?

Solenoid drivers are still required for reduced turn on and turn off times. The customer can select the system they prefer. Nordson offers their 2 gun MEG Driver and Sencon offers a standalone 4 gun system. The Sencon system can be ordered with voltage controlled cards (for conventional guns) or current controlled cards (for MEGII guns).


CTI specializes in machine and line control solutions for the two-piece metal container food and beverage industry. This high speed timing application was developed to accurately control lacquer spray timing without the use of an external timing device.

Our team has been providing innovative software solutions to the can line industry for over 20 years.
 


Is Low Spin Detection Included?

Low spin detection is included as part of the software package. The number of revolutions the vacuum wheel must make is user settable. No additional components or hard wiring is required to implement this feature.

Spinner Faults are now Isolated to the Individual Turret !

With spray logic now being controlled within the PLC, other customer programs can be integrated into the system. For example with the addition of a sensor, vacuum wheel spinner faults can be isolated down to the exact wheel causing the fault. This is a standard feature of the software package.

 

High Speed Spray Timing Software
for Allen-Bradley's
ControlLogix CPU


Control spray timing directly from a ControlLogix PLC with an accuracy of ±0.02 msec.

Control Technology has developed a high speed subroutine that accurately controls spray time to ±0.02 msec. Using an Allen-Bradley scheduled output module we have overcome the scan time limitations of the CPU. The information is downloaded to the module and it handles the precise timing, independent of the ControlLogix processor. All spray machine inputs and outputs are directly wired to the PLC and are available for customer use within the ladder logic program. The PLC output card can control either the Nordson or Sencon solenoid drivers.

The ControlLogix CPU is quite fast and can easily handle a high speed interrupt routine, but the fastest interrupt that can be used is typically 1.0 msec. or greater. Also creating processor delays are the housekeeping chores and high priority motion demands placed on the system. This can easily add another ±0.5 msec. of jitter. For this reason historically the PLC platform has been unable to handle applications that require accurate timing in the sub millisecond arena. That has all changed with the Allen-Bradley scheduled output module and CTI’s high speed control subroutine. This solution has been optimized and tested for accuracy.

In addition to the elimination of an external timing box, we can measure the actual time a can is stopped in front of the spray gun. By knowing this information we can prevent an operator from entering a spray time that is too large. An external black box timer doesn’t have this information available to it. Consequently, the spray gun could possibly be on while the can has moved out of position.

Advantages of the Software Solution

The high speed software provides a lower cost more flexible solution. Spray time settings that formerly were entered via external switches can now be entered through existing operator interface terminals such as PanelView Plus.

Since all PLC inputs and outputs are directly controlled through the program, line reporting and quality control information is immediately available. Data such as exact can counts and time of day when the spray weights were changed is easily integrated into the plant reporting system. Measured spray weights can be entered into the same operator interface and correlated in real time.

 SAFETY FEATURES

Shift registers are cleared on machine stoppage to prevent accidental gun operation.
Can-in-Pocket sensor can’t be triggered when machine is stopped.
Guns turn off if the spray time is set too long and the station starts to index.
Manual spray operation is only allowed if machine is stopped.

 BENEFITS

Allows use of existing ControlLogix hardware to control spray timing functions.
Lower total system costs while increasing flexibility.
Can handle the new MEGII guns.
More reliable because of decreased number of components and wiring.
Allows spray times to be set through an existing operator interface terminal.
Remote control and monitoring over the plant network.
Alarm notification if the spray duration setpoint is greater than available dwell time.
Easy system troubleshooting using standard PLC tools.