By John Gmutza, Principal Engineer
Innovative technology that promises reduced scrap and waste, cost savings and quality improvement is popping up everywhere in the manufacturing industry. But when it comes to Manufacturing Execution Systems (MES), there are a number of trends to avoid in your long-term strategy for growth.
Trend: Controls-Based Manufacturing Execution Systems
Controls-based MES have direct PLC-level integration of the operation’s process, without the aid of a separate operator workstation. When a process engineer configures a process, the system generates the appropriate logic for direct consumption by the PLC.
The ever-increasing complexity of content and error-proofing will tax the limits of controls-based MES. Why isn’t this good for a long-term strategy?
- Limited ability to collect bar codes for job identification and content selection based on bill-of-materials.
- Inability to process multi-field barcodes, i.e., a 2D barcode “data block” with multiple AAIG fields present (part number, serial number, etc.).
- Inability to directly communicate with databases or web services to look up recipes and save results.
Running with this type of MES is a controls “black box.” From our experience, we found that manufacturers typically do not have the ability to troubleshoot the “guts” of the logic or make new building blocks to extend the PLC program.
Don’t like the tools that controls-based MES provide? Too bad! You are now backstage at Project Runway, and you better “make it work!”
Trend: Purchasing MES Based on Cost, Not Capabilities
When purchasing systems to run your lines, buying based on cost and not based on the capability of the system is a painful rising trend. These “low-end” MES are no more than glorified process data collection systems.
You can tell an MES is low-end by the “after-the-fact” controls integrations with little-to-no capability for interlocking with the machine and controlling the process. These MES are appealing from a cost perspective, but ill-equipped to track individual pieces and provide the necessary supporting data (e.g., bill-of-materials and barcode data collection) to ensure correct execution of any process and content.
Trend: OPC See Ya!
OPC infrastructure gains attention from its (potentially) centralized point for management. However, most people don’t see that this is also a single point of failure. Connecting an OPC server with its remote clients is as complicated as firewall configuration.
This centralized approach is a challenge for the network because every PLC that participates must be “visible” on the OPC server’s network. Without the proper network administration, all the traffic “piles on” the facility-wide network, instead of confining to a private network segment. So really there are two points of failure: server and client. This means troubleshooting just got two times harder.
Trends come and go, but when considering what kind of MES fits into your strategy, plan for long-term growth, not cheap, short-term fixes.