Martin Control Systems, Inc.

Production Monitor

With three IBM personal computers (PCs) connected to a mainframe computer and communicating with a network of six Yaskawa GL60 PLCs, this production supervisory system is able to receive daily production schedules and monitor vehicle production along an automotive body welding line.   

As the shift progresses, the master PC collects data from the PLCs to track actual production.  This is compared to a calculated production count that is based on the amount of time worked on the shift.   

Shift leaders can adjust for scheduled breaks and overtime as needed to meet production goals.  Minute by minute production standings are displayed in a tabular format on large color TV monitors located throughout the production line area. 

Labeling Conveyor System

This retrofit started with a system review and investigation of an existing single filer conveyor system, splitting one conveyor lane into two.  

In order to eliminate jams at the split, a new conveyor section was installed.  Control of the entire line was converted from a Modicon 984-B to a new Allen-Bradley PLC-5/15 and eleven Allen-Bradley 1333 variable speed drives.  This required the design of a new 3-door enclosure, associated wiring drawings and fabrication.  New PLC logic was developed to optimize the features of the Allen-Bradley drives and gain better overall control of the line.  Preparation of electrical contractor bid documents was provided, as was participation in the bid meetings and walk throughs.  On-site installation supervision of the electrical installation was provided during a two-week shutdown period. 

Centralized Control of a Chemical Plant

Automation of an existing chemical refinement plant was accomplished with Allen-Bradley PLC-5/20s and an MS-Windows based MMI package.  Up to six remote computer nodes were connected via thin-Ethernet.  Datahighway Plus was used to network the PLCs.  External Johnson Yokagawa PID loop controllers were tied into the MMI via an RS-485 network and supported remote set point control, loop tuning and process monitoring.  Using a “drill-down” approach to the MMI menu structure and indirect variable addressing, this extremely large application is very manageable and efficient.  Electrical drawings, training and start-up services were also provided.  

High Speed Label Applicator

This retrofit project replaced an old clutch / brake system with a faster and more accurate servo motion system at a local pharmaceutical firm.  An Allen-Bradley SLC-100 was replaced with a Modicon Compact 984 with a BMOT-202 motion control module.  Conveyor and indexer control was converted to the new PLC and interlocked with the servo driven applicator head.  An operator interface keypad was provided to allow setup of up to six different bottle sizes.  

Batching System Enhancement

Adding a new rack of Allen-Bradley I/O to an existing PLC-5/20 based plastic batching system allowed enhancements with Rosemount tank level detectors, a Miltronics ultrasonic silo measurement system, and Micromotion mass flow meters.  Totalized material flow was accomplished with an Allen-Bradley CFM module.  An almost total revamp of an existing Wonderware InTouch MMI system and several new screens yielded advanced system alarm monitoring and diagnostic capabilities.  On-site panel equipment installation, wiring changes and software debugging took place during weekends and shift changes to meet a zero downtime requirement. 

RFID Project

An RFID system was implemented by an auto manufacturer to help assure proper routing of subassemblies through the various operations in the weld shop. 

To conserve floor space, an overhead rail conveyor system is used for temporary storage and movement of the auto body subassemblies.  Drop/lift stations transport the bodies to and from self-propelled carriers that move about on the rail system.  

A PLC tracked the location of each carrier by using proximity sensors located throughout the conveyor system.  Model code and body style information was held in the PLC memory stack.   

From time to time, errors occurred when associates accidentally and unknowingly activated the proximity sensors as they worked and moved about in the overhead rail conveyor areas.  This would lead to a mismatch of model codes at the destination drop stations requiring a temporary halt to production while the mismatch was traced and corrected manually. 

To prevent the accidental mismatches, the RFID system was introduced.  An RFID carrier tag was mounted on each parts carrier and an RFID sensor was mounted at each drop/lift station and connected to the conveyor PLC via DeviceNet interface.   

The model information can now be written to the RFID carrier tag as the body enters the weld area and is subsequently read back at each drop/lift station.  The information is passed back to the conveyor PLC, which verifies the identity of the subassembly thus assuring proper routing. 

When the subassembly leaves the weld shop, the RFID tag is erased by the conveyor PLC and prepared for the next subassembly.