Oems…Still Building with ARCNET by Joanne Harris and Steve Mack

OEMs…Still building with ARCNET By Joanne Harris and Steve Mack

The choice of communications solutions boils down to one Smart Trac has an expansion port that is PC/104-compliant to factor: meeting the customer’s needs and expectations. As one allow for several communication option boards (such as of the original networks with over 20 years of field use, ARCNET) or for expanded I/O. In summary, the functions of ARCNET continues to be a popular choice for many OEMs. the board include:

■ execution of the user’s program MagneTek Drives and Systems Division in New Berlin, ■ communication with the motor drive inverter control board Wisconsin, for instance, has embedded ARCNET PC/104 cards ■ communication to users via an IBM PC compatible computer from Contemporary Controls (Downers Grove, Illinois) into or hand held terminal the soon-to-be-released Smart Trac motor drive family (see ■ accommodations for PC/104 option board(s) Figure 1). “The whole reason we went with PC/104 is because we can buy a board from multiple vendors,” explained Steve Mack, Man- ager of Circuit Design and Software Development at MagneTek. “We could make them ourselves, but it would take longer and we would incur a development expense. We can just concentrate on the software, which will allow us to bring new features to market sooner.”

Motor drive with Smart Trac The list of features made possible with the Smart Trac drive family include:

■ programmable using the programming languages specified in IEC-1131-3 ■ isolated RS232 serial port for PC communication ■ RS232 serial port for communication with a local operator (keypad/display) ■ PC/104 expansion bus connector Figure 1 ■ minimal firmware on the option board to allow programming ■ transmit application programs to/from the Smart Trac via an This latest-generation motor drive is targeted for a myriad of IBM PC compatible computer applications, including: ■ diagnostic software for application program interrogation (tracing, forcing, trending, and so on) ■ converting and paper-mill applications (systems and ■ additional function blocks for programming languages to standalone) keep the functionality currently available in the existing ■ supercalenders MagneTek block language ■ metals process lines ■ optional PC/104-compliant ARCNET board for communica- ■ machine tooling tion to other devices on the MicroTrac LAN ■ winders ■ crane and hoist operation In addition, the Smart Trac also provides: ■ elevator controls ■ palletizing ■ 486 processor ■ Floating Point Unit The Smart Trac drives can be programmed individually for a ■ 2 megabytes of programmable flash ROM (minimum) specific function and core purpose, thereby eliminating the need ■ 4 megabytes of RAM for a central processor to coordinate drive activities on a ■ 512 bytes of dual port RAM (DPRAM) machine or process. MagneTek wanted to provide easy-to-use ■ 8 kilobytes of nonvolatile RAM program languages and an environment that would be accept- ■ battery-backed, real-time clock able to integrators and large users with a technological back- ground. The Smart Trac embedded PC is installed parallel to and above the inverter control board. Up to two communication or I/O The drive incorporates the company’s Smart Trac technology, option boards can be mounted parallel to and directly above the which allows quick programming for custom applications and embedded PC. The communication or I/O option boards com- easy expansion for communication or extra I/O. The Smart Trac ply with the PC/104 Specification, which dictates board dimen- includes an embedded PC printed circuit board that may be pro- sions, connector type and location. grammed using the five programming languages specified in IEC-1131-3. This programming flexibility ensures users of a The package that encloses all of the electronics also houses the familiar interface. local operator to allow the user to view the display and touch

Reprinted from PC/104 Embedded Solutions / Summer 1998 / 1 Copyright 1998 ~ All rights reserved the keypad. The local operator can be electrically connected to signals are funneled into DPRAM and drive status information the Smart Trac via a ribbon cable. One of the initial design goals is read from the DPRAM. for Smart Trac was a package that would be easy to assemble and disassemble. As illustrated in the Figure 2 diagram, the PC/104 port permits an array of option boards to communicate with Smart Trac. Accessibility is also a key factor, ensuring that all PCB connec- Some of these boards, such as the ARCNET PC10420-CXB, are tors, test points and LEDs are accessible without disrupting the designed and manufactured by Contemporary Controls. Others board stack. With the exception of the inverter control board’s are designed specifically by MagneTek for optimization pur- terminal block, all connectors are pluggable, which sidesteps the poses. This array of communication boards gives the user need to remove holding screws. A means is also provided to greater flexibility of protocols. hook up to the Smart Trac RS-232 serial port after the drive cover has been installed. In addition, two RS-232 serial communication ports exist on Smart Trac. A non-isolated port is dedicated to the local opera- IEC-1131-3 compliant languages are used in a Microsoft Win- tor. Drive functions can also be accessed here, such as: dows environment, and MagneTek incorporated its own algo- rithms and expertise into the software. From a software/firm- ■ run/stop ■ parameter settings ■ status and diagnostics ware viewpoint, the PC provides user-friendly tools for developing a drive control program. The developed program is then An isolated port also exists for use by either a PC or a hand held downloaded to the control board for execution. terminal (such as MagneTek’s Portable Control Display Unit - PCDU) for diagnostics and application monitoring or manipu- The control board holds PC/104 expansion boards which per- lation. mit communication with the outside world. It also accesses several other types of hardware essential to industrial control and Any information exchange between Smart Trac and the periph- operation. A diagram of Smart Trac I/O is shown in Figure 2. eral hardware must take place via a software driver. Among the primary software driver functions are: Data transfers to and from Smart Trac are confined to: ■ data packet construction ■ data parsing ■ the DPRAM ■ PC/104 bus ■ error checking ■ data transmission ■ RS-232 serial communication ports Additionally, each driver handles functions specific to the The DPRAM is the only means of communication between the inherent nature of the I/O addressed. For example, the I/O driver Smart Trac embedded PC and the inverter control board. Control for the inverter control board dual-port memory must complete

INVERTER CONTROL BOARD DPRAM

PG-SC BOARD ARCNET SMART TRAC PC/104 DEVICENET ETHERNET PROFIBUS

LOCAL FIBER OPTIC OPERATOR RS-232

RS-232 (ISOLATED)

PCDU Figure 1 COMPUTER

2 / Reprinted from PC/104 Embedded Solutions / Summer1998 Copyright 1998 ~ All rights reserved a rather complex initialization procedure with the drive before Joanne L. Harris is the marketing any drive parameters can be written or read. This procedure is communications manager for Contempo- part of (and confined to) the DPRAM I/O driver. rary Controls, developing and producing press materials, application stories, The Smart Trac software includes drivers for the following: advertising and technical documentation. She is a graduate of the University of ■ ARCNET Central Florida, with a degree in Journal- ■ Ethernet ism, PR, and Advertising. ■ PG-SC board ■ Inverter control board dual-port RAM Steve Mack serves as Manager, Circuit ■ RS-232 communication for a PC Design & Software Development at ■ RS-232 communication for the local operator MagneTek Drives & Systems. Steve has ■ RS-232 communication for the PCDU worked in New Product Development since joining MagneTek in 1988. He ARCNET network advantages holds a BSEE degree from the University ARCNET (Attached Resource Computer NETwork) is a local of Wisconsin in Milwaukee. area network (LAN). It connects up to 255 nodes in a star or bus topology at 2.5 Megabits per second over twisted pair, optical fiber, or coax medium. ARCNET utilizes a token passing For more information, contact Contemporary Controls or scheme to determine which node has momentary control of the MagneTek Drives & Systems directly: network. When a node receives a token, it has the right to ini- tiate a transmission sequence or it passes the token to the next John Kessler – Contemporary Controls node. Tel: 630-963-7070, Ext. 112 • Fax: 630-963-0109 Email: [email protected] ARCNET communication complies with standard ANSI/ATA 878.1 Local Area Network: Token Bus (2.5 MBPS) Standard, Ken Gniot – MagneTek Drives & Systems and its protocol complies with MagneTek’s MicroTrac Local Tel: 414-782-0200 • Fax: 414-782-3418 Area Network Protocol. This driver honors the MicroTrac LAN- Email: [email protected] addressing scheme consisting of Website: www.MagneTekDrives.com

■ node ■ channel ■ subchannel Faster (and slower) ARCNET chips are here Developers within the PC/104 marketplace will be able A mechanism is provided which permits synchronization be- to expand their design options with new chips from the tween multiple Smart Trac drives and coordinates all applicable Embedded Networking product line, developed by Standard Smart Tracs on the same network. Microsystems Corporation (SMSC).

An ARCNET communication board allows the Smart Trac to be Utilizing an ARCNET protocol engine, the COM20019 and the compatible with existing MicroTrac LAN products. The board COM20022 are general-purpose communications controllers conforms to the PC/104 Specification in regard to form and fit. for networking microcontrollers and intelligent peripherals in industrial, automotive, and embedded control environments. The ARCNET electrical interface utilizes a high impedance transceiver to allow bus-type LAN connections to be made. A These devices allow developers the flexibility of selecting from BNC type connector is provided to attach the LAN coaxial various baud rates of 19 Kbytes/sec up to 10 Mbytes/sec. Dif- cable, and an eight-position DIP switch is included for the func- ferences in speed meet varying application needs: slower con- tion of setting the LAN address (from 1 to FF hex). The trollers where long distances are the major consideration, and ARCNET controller generates an interrupt upon receipt or trans- faster controllers when high data throughput is the key issue. mission of a LAN packet. Where cost – and not speed – is the primary consideration, the Summary COM20019 is the answer. This chip offers an affordable so- Representing just one of the innovative OEM applications uti- lution to applications within the building automation (HVAC lizing ARCNET, the Smart Trac motor drive family from control) and point-of-sale terminal (fast food) markets. The MagneTek is scheduled for availability in the third quarter of faster baud rate of 10 Mbytes/sec provided by the COM20022 1998. To learn more about ARCNET and ARCNET Trade As- is well-suited to such markets as: sociation (ATA), contact George Beason, executive director, at [email protected], or at www.arcnet.com. The ARCNET ■ motion control ■ motor control Trade Association (ATA) is a non-profit organization consist- ■ valve supervision ■ conveyor control ing of users of end products, developers/vendors of products, ■ transportation (airline entertainment) dealers, distributors, re-sellers and system integrators, and others interested in the ARCNET fieldbus technology. The ATA is In addition to supporting numerous cabling options, these con- an ANSI Standards development body that exists to develop trollers deliver the flexible benefits of an open standard pro- ANSI standards for ARCNET products, and to provide infor- tocol (ANSI-878.1). mation and support for members. The Standards Committee is currently revising the 878.1 standard to include the higher 10 For more information on these new controllers or the Embed- Mbytes/sec data rates that are soon to be released. Ω ded Network product line, contact Fred Weber at fred. [email protected] or visit the website at www.smsc.com.