Wireless aids molding machine ERP

By Jim Montague, Executive Editor

It’s ironic that sometimes even high-flying software needs some help from meat-and-potatoes industrial networking hardware. It’s doubly ironic if that hardware is wireless.

This was the case for Cornucopia Tool & Plastics of Paso Robles, Calif., which uses a variety of injection molding machines to produce a wide line of plastic products and injection machine molds. The company partnered with Integrated Quality Management Systems (IQMS) of Paso Robles, a developer of enterprise resource planning (ERP) software, and wireless hardware developer Crossbow Technology in San Jose, Calif., to beta test a wireless data handling system.

When reconfiguration or relocation of machines is required frequently due to product demand, any associated disconnection and reconnectionof the ERP system—sometimes involving rewiring—can be daunting. This wireless system eased the problems associated with machine relocation.

The IQMS system Cornucopia uses evaluates signals every time its assigned work-center completes a cycle, and helps to route resulting products to the next center or to an inventory management system. The software also tracks raw material use, labor, and overhead costs.

The data stream from the work-center reports whether it’s running, and the bill of materials shows whether that machine should be running. This allows users to track their application up and downstream, and enables them to potentially run leaner.

IMQS has developed enterprise resource planning  software since 1989 for manufacturing users, especially for plastic injection molding and die-cast metal applications. The company added a real-time production monitoring module in 1993, and its EnterpriseIQ (EIQ) system has been hooking simple sensors up to machines since 1997.

	FIGURE 1: RUNNING ON BOARD
	The beta test involved plugging a wireless board into an sister board with a sensor.

Flexibility = Freedom
To help remove hardwired restraints that companies such as Cornucopia and others experienced, IQMS researched wireless technologies, and eventually developed its wireless hardware and software with help from Crossbow. In essence, IQMS plugs Crossbow’s two-year-old Mica-Z wireless board into an IQMS sister board with a sensor (See Figure 1). The board is powered by low-power battery. This two-board solution then goes onto each machine that a company such as Cornucopia wants to monitor. These boards communicate with one gateway board that Crossbow installed at each facility.

Instead of going over the usual wires, data now travels at 2.4 GHz over an IEEE 802.15.4 Zigbee physical layer. This network is arranged in a automatic-routing, self-healing mesh configuration, which allows its data packets to hop to the closest hub (See Figure 2 below).

FIGURE 2: RUNNING ONBOARD

Two boards are used to reach a wireless gateway and deliver injection molding machine data to higher level systems.

These routing parameters usually are built into the wireless system’s software (See Figure 3 below).

FIGURE 3: WIRELESS SOFTWARE LEVELS

The wireless board’s software operates on three tiers.

“Our stress testing showed the network can handle signals every 0.6 seconds. When the distance to the gateway becomes too long, we can just add another wireless mote,” says Randy Flamm, IQMS’ president. “When we’re dealing with real-time signals, some latency gets added when a signal goes into the Oracle database. In a wired environment, a real-time, PC-based server watches these signals. So, it required us to do some development to eliminate this latency in our new wireless environment.”

As with most wireless networks, maximum distance between transmitters and their gateway can vary widely depending on how crowded a location is with heavy machinery, electrical interference, and/or other obstacles. The boards in this solution operate with a maximum distance around 100-250 ft. before another node is needed, according to Joerg Bertholdt, Crossbow’s marketing vice president.

“Early on, we saw that our board also needed some additional filtering because it was picking up some interference at 60 MHz on some of the 10 V components,” adds Bertholdt. “We took more queries from the database, and again compared the wired and wireless performances to locate the problem. The hardware indicated that we needed to supply better earth grounding to solve the problem at 60 MHz.”

Evaluating Wireless
After building their wireless boards, IQMS, Crossbow and Cornucopia began the beta tests. The price tag for IQMS and Crossbow’s experiment also wasn’t too burdensome for Cornucopia. It cost $300-500 per machine to outfit them with wireless boards, plus another $60-100 overall for 1,000 ft. of cabling arranged in a star topology. Flamm reports that a similar hardwired solution would have $700-900.