The revised control system has been designed to replace the original dedicated controller which was no longer useable or serviceable. A priority was to keep the costs as low as possible and it was decided to implement the controller using various interface components, a standard PC with a specialized counter interface card and software written to replicate the original machine functions.With the introduction of a PC other possibilities arise – such as data logging, ethernet networking facility for remote machine monitoring and production monitoring. Initially the brief was simply to replicate the original machine functions and the various enhancements can be done at some later stage.
Basically, the machine is used in four distinct operating stages – batching on, processing, balancing, and batching off.
The software provides a manual mode for batching on and batching off. In this mode the operator has preset drive motor control setpoints three in each direction for the drive motors and three for the unload motor. In this mode ramping control is always active in order to reduce the start-up and stopping stresses on the fabric.
Balancing is the process during which the fabric is kept moving while other things are being done such as sample analysis, draining the bath or getting the bath up to temperature. When balancing the fabric is wound a preset number of turns in each direction at a preset speed indefinitely. Balancing is started automatically after processing is complete to give the operators time to prepare for the next part of the process.
Processing, as the term describes, provides the facility to run the fabric through any number of ends at the preset fabric speed. The operator fills the bath and adds the various chemicals as required, then gets the bath up to the desired operating temperature. When the bath is ready the fabric can be processed. During processing the operator can pause the process to take samples, make any adjustments necessary and then restart the process.
After processing is complete the system automatically goes into balancing mode and the orange strobe flashes to indicate to the operator that his attention is required.
Functional Block Diagram
[in this mode all motor controls can be operated manually. The counters can be reset as required. Used for batching on, batching off and all other manual functions. Note that the unload motor cannot be used if the main motors are being used and the main motors cannot be used if the unload motor is not OFF. Three preset motor speeds can be selected for the main motors and the unload motor. The preset values are set as a percentage of the drive to the motors and are adjusted in the SETUP|SETPOINTS section]
[In this mode the cloth can be wound from roller to roller automatically any number of preset times –
The fabric linear speed setpoint cannot be adjusted by the operator - this must be done in the SETUP|SETPOINTS section]
The following is displayed:
The number of ends selected
The number of ends completed
Status of the various alarms and warnings
Left and Right Motor Rotations
Emergency stop button
Fabric run length
Fabric linear speed
Process start time
Fabric linear speed setpoint
Hydraulic oil temperature
The operator can change:
Number of ends
Bath temperature setpoint
Heating steam selection Off/Indirect/Direct]
[in this software version only the hydraulic oil temperature alarm value can be adjusted. No action is taken if the oil gets to this temperature except that as an interlock a new process cannot be started. Other alarm settings and actions can be added in the future]
[In this section the ramp control settings can be adjusted for the main motors and the unwind motor. A smaller ramp value slows the ramping down and a larger value speeds it up. Recommended is 0.5 for the unload motor and 1 for the main motors. An adjustment is also provided for the main motors Direction Change Deadband – this is the setting from the null point at which the motor control valves changes from driving to trailing operation – it should not be necessary to adjust this. Recommended value is 3%]
[In this section the following can be adjusted:
Fabric linear speed setpoint, the balancing speed % and number of balancing revolutions, the manual speed presets for both the main motors and the unload motor]
[This selection provides access to the program timing settings, low level configuration settings and various diagnostic functions and controls. Changing settings without detailed knowledge of how the software works may cause the system to operate unpredictably.]
[Allows adjustment of the following:
Scaling the analogue inputs,
Fabric linear speed pulse settings, speed wheel circumference and number of speed measurement averages (this sets the filter/average length for the measurements from the speed sensor input),
Fabric reset run length – clears the fabric length integrator,
Datalogging filenames, datafile header and datalogging ON/OFF selection,
Fabric No Speed Setpoint (speed value below which fabric is deemed to have stopped)]
[Allows adjustment of the base clock, the watchdog counter, the graph update counter and the log interval counter.]
[This section allows access to various settings and displays used during the program development. Should only be used by someone who understands the software operation.]
[Displays all the PIT counters on the DT042 card with the counter controls and provides the facility to reset and configure the operation of the 8254 counters. The balancing latched right motor counter value is also displayed.]
[selects motor controls – OFF; Manual Separate; Dual System - should be Dual System for everything except diagnostics and fault finding. Both the main motor and the unload motor ramp outputs are displayed as well as the fabric direction control value]
[The speed controller settings can be adjusted while displaying the various diagnostic values. For a description of the various parameters and their effects on the speed control you could refer to the New Testament.]
[This selection provides manual override controls for all the digital inputs and outputs]
[In this section you can adjust the number of temperature measurement averages made as well as the temperature control hysteresis value.]
Typical Fabric Speed Control Performance
SafetyThe Emergency OFF latching push button must be used before any operation is carried out that involves working with any of the parts that can move.
Power FailuresIn the event of a power failure the PC and the MCI enclosure will remain on for a period until the battery of the UPS is exhausted. When the PC shuts down due to a power failure the fabric will require to be rewound and the counters reset. Should this be inadequate, either a UPS with larger battery capacity can be used, or the software can be enhanced to save the counter values when a power failure is detected and then restore them once the power supply resumes.
I/O Allocation Information and Power Up Configuration
Future System Possibilities
Automate the direct and indirect steam selection during temperature control.
Add temperature and fabric speed warnings and alarms when processing for improved quality control.
Add automated bath filling and draining to speed up the processing of the fabric.
Produce a batch processing report – this could include temperatures used, speed, standing time, processing time etc. – this to ensure consistent product quality and to meet any production certification requirements. Could also be used to schedule preventative maintenance functions based on cumulative machine operating time.
Add recipe selection so that the operator doesn’t have to change settings manually, he will simply be prompted to perform various actions when required – such as batching on, adding reagents and batching off. This would provide consistent product quality at optimum machine throughput.
Provide remote machine monitoring using Ethernet network.
Provide automated e-mail summary reports giving batch details and machine monitoring functions.
Enhance the alarms and warning functions to optimize operator interaction and increase throughput.
Enhance the software to save the counter values when a power failure is detected and then restore them once the power supply resumes. This will reduce down-time in the event of a power failure.