DNC Concepts and DNC Hardware

BTRs & DNC Software
Advanced Digital Research, Inc. the leading supplier of DNC (Distributed Numerical Control) hardware and software

BTR and DNC Concepts

Hand held terminal makes operating easy

EXEC tapes the easy way

Cables and settings.

Topics:
Why network machines?
What is unique about machines?
DNC Implies use of Server Computers
Networking
Ethernet Networks

Machines

Why DNC?: Simply put, you need to connect your shop floor with your engineering and business systems. Or briefly, as manufacturers move from functional structure to Process-oriented structure they "decentralize" to gain flexibility and quality. Originally Distributed Numerical Control (DNC) was used to save time and money over manual methods of loading programs, or using punched tape. Today DNC is an essential element of CIM and production logistics. Networking eliminates errors, and gives all machines a unified way to access files. Network security features keep your files safe. Programs in CNC memory can be saved easily and rapidly, so you will not loose edited files. DNC is constantly improving, and you now have more affordable options than ever. You do not have to buy new machines, or buy an expensive "DNC" options from the machine manufacturers to gain the improvements provided by DNC. Advanced Digital Research Inc. specializes in providing networking for all types/brands of machines.

Machines: Factory machines have a specialized computer in them, called the "control", that controls the machines motion in real-time. The machine actions are determined by a program - a command is called a block. Older machines may not have memory and execute blocks fed to them from a tape reader(NC machines). ADR's BTR supports hundreds of different NC/CNC models. We supply cables needed to attach the BTR to the control and have application notes on how to configure our BTR for almost every control. A CNC (computer numerical control) has memory and "devices" (RS232 ports) to move data in and out of its memory. Some CNC can only execute programs from their memory, others can "drip-feed" - execute from an input device, while reading ahead a few blocks. RS232 has been around a long time, and was originally intended as the standard for hooking modems to computers and terminals. A modem allowed connection to the public phone system for long or short distance communication. Now days we "direct connect" CNC to computers using RS232, or use "bridges"(modems) to connect via Ethernet, BlueTooth, USB and other communication "media".

DNC Server Computers:

Hardware Evolution

USB

The primary role of a DNC server computer is to store programs, and to send and receive data files. A DNC Server Computer in simple terms is any computer running a DNC service program. A network of PC DNC server computers can act like a single large DNC server computer. A DNC server computer can also be used to create new programs or edit programs, but the activity is usually done on graphic workstations (or PCs) with CAD capability. Windows has become very popular in manufacturing, due to its low cost and high performance.

PC manufacturers are no longer providing RS232 ports and Parallel printer ports on PCs. So applications supporting serial ports and parallel printers require 3rd party hardware which duplicates the legacy COM port interface capabilities.

PCI bus slots PCI Express has displaced the 32bit PCI bus. PCI-E uses a very high speed serial protocol, providing high speed data and low cost due to smaller connectors. Multi-port Serial adapters requiring PCI slots are loosing popularity.

The Universal Serial Bus is intended to connect printers, scanners, keyboards and mice as well as hard drives to the PC. DB9, DB25 serial ports and DB25 printer port connectors are not provided on new PC, because of the popularity of USB. USB is capable of delivering data at a high rate. RS232 ports connected via USB tend to have limitations compared to the serial ports that used to be on the motherboard or provided in a ISA or PCI slot. The problem is that USB is far slower to respond to interrupts, making "Drip-feed" impossible.

Windows

Microsoft Windows is the defacto standard in manufacturing. Windows 2000/XP/VISTA are far superior to earlier versions of Windows, which did not support "Plug and Play" and were much harder to configure. These newer Operating systems are derived from the "NT" kernel, and the serial communications capability starting with Windows 2000 has remained virtually unchanged. This means new and old application can continue to use RS232 serial ports.

Networking Machines

DNC means connecting the company database with machines. You might dedicate a personnel computer to each machine in your shop, or you might support all of your machines from one central computer. ADR can provide you with software and hardware applicable to both of these choices.

Drip-Feed

When the NC program is too large to fit into the CNCs memory, it can still be run, by the PC feeding the data to the CNC as it needs it. Not all CNC can do this. The problem is to keep the CNCs buffer full of data without ever going empty, because if the CNC is "starved for data" the part being machined could be ruined. Care must be taken to insure that, no corrupted data is ever processed by the CNC, or data is lost. The PC must remain "ON-LINE" during the execution of the program, turning the PC off, or "Suspending" to save power would be a disaster.

Star network

DNC Wired Networks

Single Drop (Star) Connections radiating from a central point: this has proven to be the most reliable way to wire multiple computer and machines

RS232 A popular form of Star network is the RS232 DNC system. Since most machines support RS232 they can be directly attached to inexpensive com ports in the DNC server computer/network.

Ethernet Another popular Star network is based on 10/100/1000BaseT Ethernet. An Ethernet Hub (switch) is used as the central point and twisted pair wires carry data at 10Mbit/sec, 100Mbit/sec and 1Gbit/sec.

These type network are often described as server/client. The CNC machines are "clients" and the network is the Server.

Unfortunately each machine maker developed their own protocols (procedures) for accessing files from servers, making the design of generic DNC software complex.

ETHERNET DNC Protocols

Some machines can directly attach to Ethernet, others require adapters. If your CNC does not support Ethernet you can connect the CNC's COM port via an Ethernet COM port. You can then use COM software to transfer files via the COM port. This allow you to use Ethernet cables, but the transfer rate is slow.

FTP (File Transport Protocol) built on TCP/IP) is standard procedure for accessing server files. Some CNC have a FTP client access built in. To use this feature, the CNC establishes a session with an FTP Server, .

Wireless Ethernet DNC Who needs wires? Where we are going we wont need wires. Seriously, the use of wires is being replaced by wireless. This saves installation cost, and adds mobility.

M2M Wireless Networks

With a advent of powerful handheld device such as the iPhone. The ability to store huge NC files in flash memory and handle it with easy became possible.

Data transfers can be directed from the DNC server called PUSH, or remotely requested at the machine called PULL.

The connection to the CNC can be an RS232 COM port, but could be via a teather (wire) or BlueTooth. The mobile device docks or pairs with the CNC to load the file into its memory.

To get the file into the mobile device it can be docked with a PC via USB, and transfered to the Mobile devices Flash memory with "iTunes" or simply Emailed to the device.