Exhibit 4.1


                         LOAN MODIFICATION AGREEMENT AND
                           AMENDMENT TO LOAN DOCUMENTS

THIS  LOAN  MODIFICATION   AGREEMENT  AND  AMENDMENT  TO  LOAN  DOCUMENTS  (this
"Agreement")  is being  entered  into as of the 3rd day of April,  2003,  by and
between  COMPASS BANK, an Alabama  state  banking  corporation  (the "Bank") and
OPTIMATION, INC., an Alabama corporation (the "Borrower"), NEMATRON CORPORATION,
a Michigan corporation, DENNIS A. SIERK and SHEILA D. SIERK.

                                 P R E A M B L E

The Borrower is the maker of a certain  Revolving Credit  Commercial Note in the
original principal amount of $450,000.00 dated June 26, 1998, as amended by that
certain  Revolving  Credit  Commercial Note from Borrower to Compass Bank in the
original  principal amount of $650,000.00 dated July 9, 1999, as amended by that
certain  Revolving  Credit  Commercial Note from Borrower to Compass Bank in the
original principal amount of $650,000.00 dated July 19, 2000, as amended by that
certain  Revolving  Credit  Commercial Note from Borrower to Compass Bank in the
original  principal amount of $620,000.00 dated June 8, 2001, as amended by that
certain  Revolving  Credit  Commercial Note from Borrower to Compass Bank in the
original  principal amount of $465,000.00 dated November 27, 2001, as amended by
that certain extension and amendment to promissory note from Borrower to Compass
Bank in the original principal amount of $405,000.00 dated February 25, 2002, as
amended by that certain Extension and Amendment to Promissory Note from Borrower
to Compass Bank in the original  principal  amount of  $385,000.00  dated May 5,
2002, as amended by that certain Extension and Amendment to Promissory Note from
Borrower to Compass Bank in the original  principal amount of $385,000.00  dated
July 5, 2002, as amended by that certain  Amended and Restated  Promissory  Note
from Borrower to Compass Bank in the original  principal  amount of  $335,000.00
dated  October  4,  2002,  as  amended  by that  certain  Amended  and  Restated
Promissory Note from Borrower to Compass Bank in the original  principal  amount
of $270,000.00  dated as of January 3, 2003, as amended by that certain  Amended
and Restated  Promissory  Note in the original  principal  amount of $225,000.00


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dated as of the date hereof (as amended from time to time,  the  "Note"),  which
evidences a certain term loan from the Bank to the Borrower  (the  "Loan").  The
Loan was  extended  pursuant  to that  certain  Revolving  Credit  and  Security
Agreement  executed  between Borrower and Lender dated June 26, 1998, as amended
by that certain  Modification  Agreement and Amendment to Loan  Documents  dated
December 15,  1998,  as amended by that  certain  Revolving  Credit and Security
Agreement dated July 9, 1999, as amended by that certain Modification  Agreement
and Amendment to Loan Documents  dated July 19, 2000, as amended by that certain
Modification  Agreement and Amendment to Loan  Documents  dated June 8, 2001, as
amended by that certain  Modification  Agreement and Amendment to Loan Documents
dated November 27, 2001, as amended by that certain  Modification  Agreement and
Amendment to Loan Documents  dated February 25, 2002, as amended by that certain
Modification  Agreement  and Amendment to Loan  Documents  dated May 5, 2002, as
amended by that certain  Modification  Agreement and Amendment to Loan Documents
dated  July 5,  2002,  as amended by that  certain  Modification  Agreement  and
Amendment to Loan  Documents  dated  October 4, 2002, as amended by that certain
Modification  Agreement and Amendment to Loan  Documents  dated as of January 3,
2003 (as amended, the "Loan Agreement"),  and is secured by, among other things,
the Loan Agreement,  Continuing  Guaranty Agreements executed by Dennis A. Sierk
and  Sheila D.  Sierk  dated  October 4,  2002,  Continuing  Guaranty  Agreement
executed by Nematron Corporation dated as of March 20, 2001, and UCC-1 financing
statements  executed by Borrower in favor of Lender.  The Bank and the  Borrower
have  agreed  to renew and  modify  the Loan,  and to amend  the  documents  and
instruments  evidencing,  securing,  relating  to,  guaranteeing  or executed or
delivered in  connection  with the Loan  (collectively,  the "Loan  Documents").
Accordingly,  the Bank  and the  Borrower  have  agreed  that the Loan  shall be
modified and renewed,  and that the Loan Documents shall be amended as set forth
below.


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                                A G R E E M E N T
NOW, THEREFORE,  in consideration of the premises,  the mutual agreements of the
parties as set forth herein, and for other good and valuable consideration,  the
receipt and sufficiency of which are hereby acknowledged,  and to induce Bank to
renew and modify the Loan,  the parties,  intending to be legally  bound hereby,
agree as follows:

A.   Modification  Fee. The Borrower shall pay to Bank in  consideration  of the
     Bank's commitment to modify the Loan, a non-refundable  modification fee in
     the  amount of  $150.00,  which  shall be  deemed  earned as of the date of
     Bank's commitment, and shall be paid on or before the date hereof.

B.   Modification  of  Loan.  The  amount  of  the  Loan  shall  be  changed  to
     $225,000.00.  The  Maturity  Date of the Loan  shall be  changed to July 3,
     2003.

C.   Amendment  of Loan  Agreement.  The  Loan  Agreement  shall be and the same
     hereby is amended as follows:

     (i)  Section  3.1  shall  be and  hereby is deleted in its entirety and the
     following inserted in place thereof:

     "3.1     At no time  shall  the  outstanding  principal  amount of the Loan
              exceed  the Borrowing  Base.  In the event the  outstanding
              principal balance of the Loan exceeds  the  Borrowing  Base,
              Borrower shall promptly  make such  principal reduction payment
              in immediately available funds as is necessary to bring the
              outstanding  principal balance  of the Loan to an amount which is
              equal to or less  than the Borrowing Base.  The  "Borrowing  Base"
              shall be calculated pursuant to the following formula: eighty
              percent (80%) of Borrower's Eligible Accounts  Receivable, not to
              exceed  $225,000.00 at any one time  outstanding, plus fity
              percent (50%) of the value of Borrower's Eligible Inventory, not
              to exceed the amount of $110,000.00 at any one time outstanding.
              Notwithstanding the foregoing, advances under the Loan shall not
              be revolving and no future advances of principal will be allowed."

     (ii) Section 8.7 is hereby deleted in its entirety and the following
          inserted in place thereof:

          "8.7  Borrower shall not make any  payments or distribute any funds to
                Nematron Corporation,  Nematron, Ltd., or any other subsidiaries
                or affiliates thereof, in excess of One Thousand Dollars
                ($1,000.00) per month, with the exception of the following:


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                (a)  Payment to Nematron Corporation for Dennis Sierk's
                     salary and benefits in monthly payments not to exceed the
                     aggregate amount of $11,343.00 per month;

                (b)  Payment to Nematron Corporation for Charles Garrett's
                     salary and benefits, in monthly payments not to exceed the
                     aggregate amount of $9,578.00 per month."

     (iii) Section 8 is hereby amended by inserting the following  provisions
           8.9,  8.10,  8.11, 8.12 and 8.13:

           "8.9  Borrower shall maintain, serve and invoice directly all of
           Borrower's customers, with the exceptions, however of:

           (a) with respect to that certain  product  known as "Pointe
               Controller,"  which may be sold and invoiced by Nematron
               Corporation;  provided,  however,  that Borrower shall be paid by
               Nematron  Corporation  for at least  Borrower's  direct material
               costs for such product, plus twenty  percent (20%), within ten
               (10) days from the date Nematron Corporation,  Nematron, Ltd., or
               any other subsidiaries or affiliates thereof receive payment for
               such product from their respective customers, and in no event
               later than 45 days from the date of invoice from Borrower, which
               invoice Borrower agrees to promptly issue; and

           (b) with respect to those certain products known as the "Legacy"
               products, orders for which may be received and invoiced by
               Nematron Corporation for joint customers of Nematron Corporation
               and Borrower;  provided,  however,  that Borrower shall be paid
               by Nematron  Corporation  for at least  Borrower's  costs for
               such product, plus twenty percent (20%), within ten (10) days
               from the date Nematron Corporation, Nematron, Ltd., or any other
               subsidiaries or affiliates thereof receive payment for such
               product from the  customers, and in no event later than 45 days
               from the date of  invoice  from  Borrower,  which invoice
               Borrower agrees to promptly issue.

          8.10 There shall be no co-mingling  of any assets, including without
               limitation, cash, Accounts  Receivables, Inventory and equipment,
               between Borrower and Nematron Corporation,  Nematron, Ltd., or
               any other subsidiaries or affiliates thereof.

          8.11 All of the Collateral shall remain at 2800 Bob Wallace Avenue,
               Suite L-3, Huntsville, Alabama 35805.

          8.12 Borrower shall provide to Bank any and all amendments to its
               Articles of Organization and/or Bylaws within ten (10) days of
               the execution thereof.

          8.13 Borrower shall furnish weekly to Bank its invoice register, sales
               register,  and cash receipts register for the immediately
               preceding week."


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D.   Effect  on Loan  Documents.  Each of the Loan  Documents  shall  be  deemed
     amended as set forth  hereinabove and to the extent  necessary to carry out
     the  intent of this  Agreement.  Without  limiting  the  generality  of the
     foregoing,  each reference in the Loan  Documents to the "Note",  the "Loan
     Agreement",  or any other "Loan Documents" shall be deemed to be references
     to said documents,  as amended hereby,  each reference to the amount of the
     Loan shall be changed to  $225,000.00  and each  reference  to the Maturity
     Date shall be changed to July 3,  2003.  Except as is  expressly  set forth
     herein,  all of the Loan Documents shall remain in full force and effect in
     accordance  with their  respective  terms and shall  continue to  evidence,
     secure, guarantee or relate to, as the case may be, the Loan.

E.   Representations and Warranties.  Each representation and warranty contained
     in the Loan  Documents  is hereby  reaffirmed  as of the date  hereof.  The
     Borrower hereby represents, warrants and certifies to Bank that no Event of
     Default  nor any  condition  or event that with  notice or lapse of time or
     both would  constitute an Event of Default,  has occurred and is continuing
     under any of the Loan  Documents  or the  Loan,  and that  Borrower  has no
     offsets or claims against Bank arising under, related to, or connected with
     the Loan, the Loan Agreement or any of the other Loan  Documents.  Borrower
     expressly  understands  and  agrees  that  this  Agreement  is  subject  to
     Borrower's  strict and literal  compliance  with the terms,  covenants  and
     provisions set forth herein, and further,  Borrower  expressly  understands
     and agrees  that this  Agreement  shall not estop  Lender  from  taking any
     action  permitted  under  the  Note in the  event  of  default,  which  may
     hereafter occur or exist under the terms of said Note, Loan Agreement or by
     reason of failure of  Borrower to pay to Lender any one or more of payments
     on said Note.  Each  individual  executing  this  Agreement  represents and
     warrants  that he or she is duly  authorized  to execute and  deliver  this
     Agreement.

F.   Additional Documentation;  Expenses.  Borrower shall provide to Bank (i) if
     Borrower or any Guarantor is a business organization, certified resolutions
     properly authorizing the transactions contemplated hereby and the execution
     of this Agreement and all other documents and instruments being executed in
     connection herewith;  and (ii) all other documents and instruments required


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     by Bank; all in form and substance satisfactory to Bank. Borrower shall pay
     any  recording  and all other  expenses  incurred  by Bank and  Borrower in
     connection  with the  modification  of the Loan and any other  transactions
     contemplated hereby, including without limitation, title or other insurance
     premiums, survey costs, legal expenses, recording fees and taxes.

G.   Execution  by  Guarantors.  Guarantors  have  executed  this  Agreement  to
     evidence  their  consent to the  modification  and  amendments as described
     herein,  and to  acknowledge  the  continuing  effect  of their  respective
     Guaranties and the obligations contained therein.

In witness whereof, the undersigned have caused this instrument to be duly
executed as of the date first set forth above.

                                            Borrower:
Attest:                                     Optimation, Inc.

By: /s/ David P. Gienapp                    s/s Dennis A. Sierk
------------------------                    -------------------


                                            Bank
                                            By: /s/ Arlene Stackhouse
                                            -------------------------
                                            Arlene Stackhouse
                                            Its:  Senior Vice President




ATTEST:                                     NEMATRON CORPORATION, a Michigan
                                            corporation


By: /s/ David P. Gienapp                    By: /s/ Matthew S. Galvez
------------------------                    -------------------------
David P. Gienapp                            Matthew S. Galvez
Its: Secretary                              Its:  President


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