Downtime Monitoring Technology

By: Steven Noto, Process Technologies Group, Inc.
Topics: Downtime Monitoring, Data Collection, IMPAX TSS

Building a networked downtime monitoring system that is affordable, reliable, and easy to use

Design Approach and Implementation

PTG originally set out to design their IMPAX Time Saver System (TSS) to monitor downtime on customers' factory machines. Now, years later, the TSS system is a comprehensive system for tracking uptime, downtime, production, efficiency, and more.

The initial goal was to develop a system to report machine downtime for customers in the fastener-making industry who were concerned with the productivity of their headers and thread rollers. Some of these machines were monitored by existing IMPAX process monitors, some were monitored by other monitors, and some were not monitored at all. A system was needed that could track production and uptime/downtime for each machine.

The original TSS was a system built with a 6-inch touch screen and a basic PLC. The PLC was programmed to count pulses from a magnetic proximity sensor positioned to detect parts as they leave the machine. The program tracked production counts, and determined downtime by calculating occurrences of 5-minute periods during which there was no signal. PLC timers and registers stored the times and counts, and the touch screen provided access to this data. When a downtime occurred, a special screen prompted the operator to select a downtime reason from a list. This information was logged in the PLC and used for analyzing downtime causes. To ensure that a reason was entered, a PLC-controlled relay was used as an interlock to prevent the machine from restarting until the operator responded. The PLC tracked all this data by day and shift.

IMPAX TSS Monitor Screen
Showing the Downtime Occurrence Log

Using one of these monitors on each machine produced a basic downtime recording system that worked very well. For data access, a simple data collection was used, built with a PC-based HMI and acquisition package, to collect the numbers from the PLCs across a serial network and display them in real time.

Over time, the system grew and evolved. As features were added, memory usage increased, so PTG upgraded the RAM in the touch screen and switched to a better PLC with twice the memory. The new PLC included additional option card slots, which allowed the use of a PLC Ethernet card to achieve much faster networking. These improvements allowed additional features to be added, such as tracking data by part number, tracking each operator log-in, tracking machine efficiencies, and allowing the user to enter up to 64 custom downtime reasons.

After the machine monitors were upgraded, the PC data collection software was switch to Microsoft Excel. Excel was chosen to provide more flexibility for future customization. A complete system was built in Excel, with screens for viewing live data from the shop floor and for reporting historical data. This data is automatically gathered by Excel periodically and saved to CSV files. Other advantages of using Excel are access to all of its charting and graphing features, and the ability to perform automatic calculations and display relevant data via Excel macros.

IMPAX TSS-NET Networking Software
Showing the Shop Floor Summary View

Custom Development

The TSS production monitoring system is now ready-to-install for most applications, but can also be customized for a particular application. The PLC program can be modified for custom workflow or to track additional types of data. For example, one customer's machines sort and count parts. The TSS program was easily updated to properly record sorted-good and sorted-bad counts, on the fly.

A Complete System

The end result of all this work is the current IMPAX Time Saver System: a complete production and downtime monitoring system, with stand-alone monitors and networked, real-time data display and collection. The system's components are affordable, readily available, and reliable. Customers are very happy with the TSS, and equip a wide variety of their shop floor machines with TSS monitors.