Kermit protocol in manufacturing

Kermit Protocol In Manufacturing

As computer-integrated manufacturing expands, user and systems integraters alike continually search for lower cost reliable methods of getting computer equipment to talk to each other. Kermit File Transfer Protocol is starting to appear on the manufacturing floor, filling the gap between low cost serial connections without error checking capability and the high cost, full capability local area networks (LAN).

There are many interface solutions available including Manufacturing Automation Protocol (MAP). The cost of utilizing these various interface methods is generally proportional to their capability and speed with LANs at the top end of the price range. The lowest cost solution to connecting computer equipment is still a serial connection provided by RS-232, RS-422 or RS-423 running very basic protocols without error checking. Most CNCs and programmable controllers today include one or more of these interfaces as standard equipment. Kermit File Transfer Protocol implemented on these controls upgrades the existing interfaces and data lines to a packet transmission type system, with check sums, and retransmission capability to enhance data integrity.

Kermit was designed by Bill Catchings and Frank da Cruz at Columbia University Center for Computing Activities (CUCCA) in 1981-82. The initial objective was to permit students that were using the university's DEC-20 and IBM timesharing system to save their files on microcomputer floppy discs. Previously all student files located on the main frames were erased at the end of each semester. The design of Kermit owes much to the ANSI and ISO models as well as to the ideas borrowed from similar projects at Stanford University and the University of Utah.

The name Kermit is derived from "Kermit the Frog" and used by CUCCA with permission from Henson Associates, Inc. Most people not directly associated with the development of Kermit try to make a meaningful acronym out of the name, but, according to Frank da Cruz no such acronym exists. The association of Kermit to the protocol was prompted by a picture of "Kermit the Frog" on a wall calendar located in the room where the development team was working. Even though there is no clever acronym, the name appears to have been wisely chosen as it always lights up the faces of those who hear Kermit protocol mentioned for the first time.

After the initial implementation of Kermit at CUCCA, it became apparent such a protocol was useful for more than just archiving files. IBM PCs, just beginning to appear in large numbers, both internal and external to Columbia University, were added to the implementation. This ultimately has led to a high demand for the protocol outside of Columbia University. The awareness and subsequent request for Kermit outside of Columbia University came about through presentations made at conferences of users groups like DECUS and SHARE. As users developed other implementations, they were fed back to CUCCA which still coordinates the distribution of Kermit.

Kermit through CUCCA's distribution program has led to Kermit being supported on over 50 different systems in hundreds of sites around the world. CUCCA estimates that Kermit has reached more than a thousand sites through various users groups and other distribution networks.

CUCCA's distribution policy for Kermit is on the basis that the software is free and available to all. Columbia University, however, can not afford to distribute free software on the scale required for Kermit. Therefore, to defray the cost for media, printing, postage, labor, and computing resources a moderate distribution fee of $100 is required. CUCCA has appointed a Kermit Distribution and Development Manager who is currently Christine Gianone and may be contacted on 212-854-5126.

Even though the Kermit protocol software is free from CUCCA, do not be surprised if there is an optional feature charge for a Kermit interface in a CNC or programmable controller. Control vendors almost always have some development cost associated with implementing Kermit into a specific control. These charges however are only a fraction of the cost of a MAP interface.

The proliferation of Kermit into the shop is primarily due to the wide variety of computers on which the protocol has been implemented. These computers when used as direct-numerical control (DNC) hosts, cell controllers, front end processors, programming systems and status gathering systems have made available a low cost interface protocol for connecting into shop floor equipment. Kermit is desirable since it runs on the existing serial data lines. Another plus is emerging out of the Binary Cutter Location (BCL) environment. Because of its packet transmission capability Kermit has become a very desirable protocol for transmitting BCL data to BCL input controls.

Even though Kermit is implemented on a wide range of computers, it is still not available on all shop floor control devices, but there is a sizeable list. The following control devices offer a Kermit protocol interface: Cincinnati Milacron's Acramatic 750 and 950 CNC Controls; GEFANUC's Series 0, 10, 11, 12 and 15 CNC offer Kermit in the MMC development mode; Siemen's RCM-3 Robot Controller; GRECO System's Versifile, Versinet and Greco-Net Products; BCL Technology's BCL Front End; ISS's Vega Series 9000 CNC.

The role of Kermit in manufacturing is not clear yet. It could be that Kermit will serve as a short term solution until MAP products become available or, it could become a long term low cost solution coexisting with MAP. Much depends on where MAP interface cost settle out.

Golden E. Herrin, Control Product Specialist Cincinnati Milacron, Cincinnati, OH 45209

COPYRIGHT 1989 Gardner Publications, Inc.
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