BTRs & DNC Software DNC Concepts
DNC is Delivering data to computer integrated NC machines
Why DNC?
Simply put, you need to connect the shop floor with 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, and 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 saves money DNC is constantly improving, and now is more affordable 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.
Computerized Machines
Factory machines have a specialized computer in them, called the "control". The control operates the machines 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 allows connection to the public phone system for long or short distance communication. Now days we "direct connect" CNC to computers using RS232, or "bridges"(modems) to connect via Ethernet, BlueTooth, USB and other communication "media".
DNC Server Computers:
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 this activity is usually done on a graphic workstation (or PCs) with CAD capability. Windows has become very popular in manufacturing, due to its low cost and high performance.
LINUX has become more popular as a server operating system because it is "open sourced", and there is less "hidden marketing" features than in Windows .
Hardware Evolution
PC manufacturers are no longer providing RS232 ports and Parallel printer ports on PCs. So applications supporting serial ports and parallel printers now use USB devices.
USB
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/Win7/Win8/Win10 are progressively better operating systems, demanding progressively more powerful computer plateforms to make them work.
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.
DNC Wired Networks Single Drop (Star) Connections radiate from a central point like spokes on a wheel. 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.
ETHERNET DNC Protocols
Newer CNC 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 (WIFI) Ethernet DNC
Who needs wires? The best wireless system almost duplicates the capability of a wire. The goal of wireless is to save installation cost, and add mobility.
Wireless Networks
With a advent of powerful handheld device such as the iPhone and iPad. The ability to store huge NC files in flash memory and handle it with easy became possible.
Push and Pull Data
Data transfers can be directed from the DNC server called PUSH, or remotely requested at the machine called PULL.