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DNC Hardware
DNC hardware refers to the physical infrastructure comprising a machine-control data communications system. The acronym "DNC " refers to either Distributed Numerical Control, where process control programs are passed to one or more Computer Numeric Control (CNC) machines, or Direct Numeric Control, where programs are run directly from a host computer.
DNC hardware provides the means by which numerically controlled (NC) machines or robots are managed through centralized process control programs and/or remote-control terminals. The machines are typically connected to common routing points through a hard-wired or wireless network. Control for each machine (or group of machines) is handled through network nodes via a series of dedicated DNC software applications.
The quality of professional DNC hardware must be several notches above that of conventional, consumer-grade electronics. DNC hardware components must operate reliably in the most demanding environments while resisting interference from machine RF emissions, yet provide flexibility and versatility to meet ever-changing production needs. These requirements are not easy to meet.
The hardware network over which a good DNC system operates requires a level of sophistication permitting uninterrupted multiple-machine control. The kinds of occasional "glitches," that can occur in conventional, consumer-grade networks cannot be tolerated in a quality DNC hardware system. Errors in machine control data result in lost time, material, productivity and, ultimately, revenue. Cable lengths must be scrupulously observed and/or interference-free wireless data paths must be established. There are also real-time monitoring and safety considerations which must be addressed. And, MES (Manufacturing Execution System) data collection and management processes may share the same network. Consequently, DNC hardware must be of the highest quality to provide the range of remote process control and environmental adaptability demanded by modern manufacturing and production facilities.
DNC Hardware Architecture
The illustration below shows a typical, physically-interconnected DNC hardware arrangement in which a series of lathes and mills are managed through distributed network hubs. The network is tied to a file server and controlled & monitored by any of several remote PC's. By adding hubs and routers as needed to service additional machines, this DNC hardware architecture can be scaled to meet the needs of a single manufacturing unit, a complete shop floor, or an entire facility, depending on the complexity and production automation requirements.
In cases where physical limitations preclude hard-wiring, a Wireless DNC hardware system can be implemented. Wireless DNC hardware provides many advantages over a hard-wired DNC system. The diagram below illustrates a typical configuration:
Aside from offering the flexibility to move machines at will and avoid clearance issues, wireless DNC hardware also provides the means to address physical machine requirements on an individual basis. For example, some machines might require wireless interconnectivity whereas others may not. Some areas may be susceptible to RF interference precluding the use of long cables, but a wireless connection usually will not suffer from this limitation.
Wireless DNC hardware also provides a practical machine-upgrade path. In the case of older CNC machines, wireless RS-232 adapters can be installed to convert the incoming NC programs from Ethernet data into RS-232 signals for input into the CNC's serial communications port. A dedicated software application runs on the DNC server and assigns a specific IP address for each of the hardware communications ports, eliminating the need for a separate serial port server.
Which DNC Hardware is Right For Us?
Wonderware's standard DNC hardware products include:
• Wireless DNC Hardware
• Serial Device Networking Hubs
• PCI Multiport Serial Cards
• Behind the Tape Reader (BTR)
• Shop Floor Terminal
• DNC Hardware Support Services
Together, these products address a broad range of functional considerations and can be configured to meet any conceivable set of DNC and/or MES application requirements. In addition, Wonderware service engineers have many years of experience in information technology and specific industry applications. They will insure that the installation and integration of Wonderware DNC hardware and software is a smooth process.
Wonderware's DNC Serial Bridge creates a wireless connection between an 8.0211B wireless LAN device with a serial port and the physical DNC control network. This wireless hardware device has been tested and certified by the Wonderware QA team to offer reliable wireless DNC. The package works with existing 802.11B wireless networks and access points, supports WEP data encryption for security purposes, support LEAP security protocol and provides a serial interface for RS232/422/485.
A typical Wonderware wireless DNC system consists of Wonderware DNC Professional™ or Wonderware Factelligence™ for Shops software and our standard wireless network components. The system typically consists of a DNC server that is networked to a wireless access point located above the shop floor. A standard Ethernet connection links the server and the wireless access point. Each wireless access point communicates via radio waves to and from the individual CNC machines.
A hardware device is attached to the CNC control to send and receive signals to and from the machine tools. The device converts signals to RS-232 input. One of these devices is plugged into each CNC machine's RS-232 serial communications port. The RS-232 converter is an off-the-shelf product developed for wireless electronic devices with Internet protocol (IP) addresses. A software application runs on the DNC server and assigns a specific IP address for each of the communications ports. This function eliminates the need for a separate serial port server and enables the system to transmit data to the correct RS-232 converting device.
In this system, security and interference are not problems. The wireless access point is designed to encrypt data at the point of transmission, and the Ethernet to RS-232 converters decode the data before the file is passed to the CNC. The system uses a radio frequency within a specific bandwidth dedicated to wireless networks. The wireless access point has security restrictions limiting the permissible IP addresses it will accept. IP addresses are assigned to the specific machines currently on the network.
Wonderware Serial Device Networking Hubs provide the fastest, easiest way to add "native" COM ports to your server via your Local Area Network. When you need to add a large number of DNC hardware data communication ports to your server, Serial Hubs and DeviceMaster hubs provide the ideal solution. These ports can reside outside your server anywhere on your LAN, keeping your server in a secure back-office location while your ports conveniently reside on the work floor. Hubs are available in 1-port, 4-port, 8-port, 16-port and 32-port models. Supports Windows NT, 2000, XP and Server 2003. Hubs are available with RJ45 and DB9 connections with RS232/422/485 capability. Hubs work right out-of-the-box and can be managed, set up and configured via a web browser.
Our PCI Multiport Serial Cards are designed specifically for small to mid-size DNC hardware installations, offering the most cost effective way to connect multiple CNC machines to a single PC or server by adding 4, 8, 16 or 32 "native" COM ports to a PC. Supports most popular operating systems including Windows ME, NT, 2000, XP and Server 2003. Both fan-out cables and serial interface boxes are available supporting DB9, DB25 and RJ45 connectors. Supports 32- and 64-bit, 3.3 and 5.0-volt PCI bus architectures. Delivers exceptional reliability and one of the industry's longest Mean Times Between Failures (MTBF). Surge protected ports are also available
The Wonderware Behind the Tape Reader (BTR) DNC hardware unit offers a microprocessor-controlled interface designed to work in conjunction with or replace a tape reader in many older CNC machine tools. A software configurable interface allows adaptability to hundreds of CNC controls. An easy-to-use operator control panel and 32K of on-board memory (expandable to 1 megabyte) handles up to 8000 tape feet of program storage. The Wonderware BTR provides machine control with RS232 or RS422 network interfaces. It is perfect for increasing the useful life of older machines by transferring unreliable paper tape to computer storage.
Wonderware's Shop Floor Terminal is a shop-hardened, environmentally sealed terminal which can be mounted anywhere in the shop. The Shop Floor Terminal is designed to replace computers in machine shops with harsh environments. They can be used for 1 CNC machine or shared between groups of CNC machines, providing directory and file scrolling on the shop floor. A supertwist, backlit LCD display makes program management easy. It offers an alphanumeric, pressure-sensitive keypad, bidirectional RS-232 and RS-422 communications with handshaking, password-protected security and many other features. The terminals are affordable and durable solutions for part program transfers and can be easily integrated into any professional DNC hardware configuration.
Wonderware provides a complete range of world-class services to add value to our DNC hardware and software packages. Our methodologies effectively guide a project through its key phases. This includes project definition and expected ROI, an assurance of solid buy-in from operations and management, design and creation of interfaces to ERP, document, labor and other systems, and development of a functional, long-term solution. We will handle hardware configuration and setup, software and database installation and configuration, and all of the associated training and documentation needed to provide complete turnkey solutions to our customers. |
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