EXHIBIT 4.3
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                                                     October 17, 2002

CERTIFIED MAIL
RETURN RECEIPT REQUESTED

Nematron Corporation
5840 Interface Drive
Ann Arbor, Michigan  48103
Attn:  Matthew S. Galvez, President and CEO

                  Re:      Loans by LaSalle Business Credit, Inc.

Dear Mr. Galvez:

                  Reference is made to that certain Amended and Restated Loan
and Security Agreement dated as of June 30, 2000, as heretofore and hereafter
amended, amended and restated or otherwise modified from time to time (the
"Agreement"), by and between Nematron Corporation ("Borrower") and LaSalle
Business Credit, Inc. ("Lender"). Each term set out herein and not otherwise
defined shall have the meaning ascribed to such term in the Agreement.

                  By our letters to you dated October 3, 2001 and February 18,
2002, we notified you that Borrower is and remains in default (collectively, the
"Defaults") under the Agreement. The Defaults have not been cured or waived. The
terms of the Agreement provide that Lender may, as a result of any Event of
Default, including any Default, accelerate the payment of all Liabilities.
Borrower acknowledges the existence of each Default.

                  Lender has requested that Borrower obtain alternative
financing, and Borrower hereby agrees to use its best efforts to obtain such
alternate financing. Borrower has therefore requested that Lender not
immediately accelerate the payment of the Liabilities, and that Lender, for the
moment, allow both parties to the Agreement to proceed under the terms of the
Agreement. In the event Borrower and each guarantor set forth herein executes
this letter and returns same to Lender on or before October 25, 2002, Lender
hereby agrees to allow both parties to proceed under the terms of the Agreement
(as such terms are amended herein) until further notice to Borrower, provided as
follows:

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     (a) That there occurs no additional Event of Default;

     (b) That there occurs no material  adverse  change (as determined by Lender
in its sole discretion) in Borrower or in its business;

     (c) That Borrower shall use its continuing best efforts to refinance all of
the Liabilities with another lender as soon as practicable; and

     (d) That Borrower agrees that the Agreement is hereby amended as follows:
(i)  The  definition  of  "Revolving  Loan  Commitment"  is hereby  amended  and
     restated to read in its entirety as follows:  ""Revolving  Loan Commitment"
     shall mean One Million Five Hundred Thousand Dollars ($1,500,000)."

(ii) The definition of "Total Commitment" is hereby amended and restated to read
     in its entirety as follows: ""Total Commitment" shall mean One Million Five
     Hundred Thousand Dollars ($1,500,000)."

(iii)Paragraph 4 of the Agreement is hereby  amended by deleting the amount "Two
     Million Five Hundred  Thousand  Dollars  ($2,500,000)"  and  inserting  the
     amount "Two Hundred Fifty Thousand Dollars ($250,000)" in lieu thereof.

                  Borrower hereby (a) ratifies and affirms its obligations under
the Agreement; (b) denies and waives the existence of any defenses relating to
its obligations under the Agreement; and (c) waives and releases any claims or
causes or action against Lender which may now or hereafter be available to it
arising out of (i) the administration of the Agreement or the Other Agreements,
(ii) the negotiation and execution of this letter, or (iii) any other matter
pertaining to the Agreement or the Other Agreements.

                  Each of the undersigned guarantors hereby (a) ratifies and
affirms its individual and several obligations under its respective Continuing
Unconditional Guaranty executed by each guarantor in favor of Lender; (b)
acknowledges and confirms that each Continuing Unconditional Guaranty continues
in full force and effect notwithstanding this letter; (c) denies and waives the
existence of any defenses relating to any of such Continuing Unconditional
Guaranties; and (d) waives and releases any claims or causes or action against
Lender which may now or hereafter be available to any guarantor arising out of
(i) the administration of the Agreement or the Other Agreements, (ii)
negotiation and execution of this letter, or (iii) any other matter pertaining
to the Agreement or the Other Agreements; provided, however, that the failure of
any guarantor to execute this letter shall not release such guarantor or any
other guarantor of its respective obligations under any of the Continuing
Unconditional Guaranties.

                  By this letter Lender does not waive any Default, nor any
previous Events of Default about which you have been notified. This letter is
being written with Lender reserving all of its rights to exercise any and all of
Lender's remedies, as provided in the Agreement and in all the Other Agreements,
at such time and in such manner as provided therein. Nothing herein shall be
construed or interpreted as being a waiver of any of Lender's rights or remedies
(as provided to Lender under the terms of the Other Agreements, the Uniform
Commercial Code or otherwise), by virtue of its forbearance to date (it being
understood that Lender has no obligation to continue to forbear) or extension
with respect thereto.

 Very truly yours,

 LASALLE BUSINESS CREDIT, INC.

 By /s/ Dale P. Grzenia
 Dale P. Grzenia, First Vice President

Accepted and agreed to this day of October, 2002.

NEMATRON CORPORATION

By s/s David P. Gienapp
-----------------------
Its Secretary

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Consented and agreed to by
the following guarantors of
the obligations of Nematron Corporation
to LaSalle Business Credit, Inc.

A-OK CONTROLS ENGINEERING, INC.         OPTIMATION, INC.

By /s/ David P. Gienapp                 By /s/ David P. Gienapp

Its Secretary                           Its Secretary

Date: October 24, 2002                  Date: October 24, 2002


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