<PAGE>

                                                                  EXHIBIT 10.511

                            [DRAFT OFFICER AGREEMENT]

                            [CYGNUS, INC. LETTERHEAD]



                                     [DATE]


[NAME]
[STREET ADDRESS]
[CITY, STATE, ZIP]

Dear [FIRST NAME]:

         This letter agreement (the "Agreement") sets forth the terms and
conditions of your employment with Cygnus, Inc. (the "Company"). All of such
terms are conditioned on your having signed and delivered a copy of this
Agreement to the Company. This Agreement has an effective date of
_________________ (the "Effective Date").

         In consideration of the mutual covenants and promises made in this
Agreement, you and the Company agree as follows:

1.   POSITION, RESPONSIBILITIES AND TERM.

         (a) POSITION AND RESPONSIBILITIES. As of the Effective Date, you will
continue to serve in the position of [JOB TITLE], an officer of the Company, as
that term is defined in the Securities Exchange Act of 1934, with appropriate
responsibilities for such role. As [JOB TITLE], you shall report directly to the
Company's [NAME OF SUPERIOR OFFICER OR BOARD OF DIRECTORS]. Your office will be
located in the Redwood City, California area and your duties shall primarily be
performed there. You will be responsible for [INSERT JOB FUNCTION].

         (b) AT-WILL RELATIONSHIP. Subject to the terms and conditions of this
Agreement, your employment at the Company is "at will" and you or the Company
are free to terminate the employment relationship at any time, with or without
Cause (as defined below) in each case subject to the terms and provisions of
Section 6.

2. SALARY. You will earn a base salary of $[DOLLAR AMOUNT] per year ("Base
Salary"), which shall cover all hours worked, payable in the time and manner
that salary is paid by the Company to employees generally, and subject to
customary tax deductions. Your Base Salary will be reviewed annually and any
adjustments will be within the discretion of the Board of Directors consistent
with the Company's policies and based on your performance and/or contributions
to the Company.

3. BONUS. You will be eligible to participate in the Company's Incentive Bonus
Plan and any other Company bonus plans if and when they are implemented by the
Company.

<PAGE>

[NAME]
December [DAY], 2000
Page 2

4. EQUITY. You will be eligible to participate in the Company's 1999 Stock
Incentive Plan (the "Plan") and any other equity incentive plans if and when
they are implemented by the Company.

5. BENEFITS AND REIMBURSEMENTS.

         (a) BENEFITS. During your employment with the Company, you will be
eligible to participate in all Company employee benefit plans and programs at
the time or thereafter made available to all of the Company's salaried employees
generally and officers.

         (b) BUSINESS EXPENSE REIMBURSEMENT. During your employment as [JOB
TITLE], you will be reimbursed for all reasonable and approved business expenses
(including, but without limitation, travel and automobile expenses) upon the
properly completed submission of requisite forms and receipts to the Company in
accordance with its business expense reimbursement and travel policies. Such
reimbursements shall be in compliance with applicable rules and regulations
promulgated by the Internal Revenue Service.

6. CONSEQUENCES OF TERMINATION OF EMPLOYMENT.

         (a) FOR CAUSE. For purposes of this Agreement, you may be terminated
for "Cause" as a result of the occurrence of one of the following:

                  (i)      Your willful misconduct or gross negligence which
                           could reasonably be expected to have a material
                           adverse effect on the business and affairs of the
                           Company or any of its affiliates;

                  (ii)     Your willful disregard of lawful instructions from
                           the Chief Executive Officer or the Board of Directors
                           (the "Board") relating to the business of the Company
                           or any of its affiliates; or

                  (iii)    The commission by you of a crime, an act involving
                           moral turpitude or an act constituting common law
                           fraud, or a felony or criminal act against the
                           Company, or any stockholder, subsidiary or affiliate
                           thereof or any of the assets of any of them.

         For these purposes, no act or failure to act shall be considered
"willful" unless it is done, or omitted to be done, in bad faith without
reasonable belief that the action or omission was in the best interest of the
Company.

         In the event your employment is terminated for Cause you will be
entitled to any accrued and unpaid salary due you pursuant to Section 2 above
through the date of termination and to any earned, unused vacation owed you. Any
accrued payroll deductions made by you under the Company's Amended 1991 Stock
Purchase Plan will also be paid to you (without interest). You will be entitled
to no other compensation from the Company.


                                       2
<PAGE>

[NAME]
December [DAY], 2000
Page 3

         (b) TERMINATION WITHOUT CAUSE OR CONSTRUCTIVE TERMINATION. The Company
may terminate your employment without Cause or you may be "Constructively
Terminated." For purposes of this Agreement, you will have been "Constructively
Terminated" if you resign from the Company within thirty (30) days after the
date that any one of the following events has occurred without your advance
written consent:

                  (x)      You have incurred a material reduction in your job
                           status, responsibilities, duties or authority,
                           reporting structure or you cease to be an "executive
                           officer" as that term is defined in the Securities
                           Exchange Act of 1934; [FOR CEO: YOU CEASE TO BE THE
                           CHIEF EXECUTIVE OFFICER OF THE COMPANY OR ITS PARENT,
                           IF THERE IS ONE, OR YOU CEASE TO BE CHAIRMAN OF THE
                           BOARD] or

                  (y)      Your Base Salary has been reduced by more than 10%;
                           or

                  (z)      An increase in your one-way commute by more than 30
                           miles.

If your employment with the Company is terminated without Cause or you are
Constructively Terminated, then you will be entitled to the following:

                  (i) SEVERANCE. One times your highest amount of Base Salary
                  and annual bonus under Section 3 above (whether paid in cash,
                  stock or a combination thereof), will be paid in one cash lump
                  sum payment within five (5) days following your termination of
                  employment. You will also be paid any earned, unused vacation
                  owed you at the time of termination of employment. Any accrued
                  payroll deductions made by you under the Company's Amended
                  1991 Stock Purchase Plan will also be paid to you (without
                  interest).

                  (ii) BENEFITS. You will also receive one (1) year of
                  continuation health and life insurance benefits (provided you
                  were receiving coverage as an employee as of the date of your
                  termination). Such benefits shall cease in the event you are
                  offered comparable benefits coverage by another employer.
                  Disability insurance coverage shall not be included in any
                  such benefits provided under this Section 6(b)(ii).

                  (iii) EQUITY. 100% of your then-unvested stock options and
                  restricted stock, if any, shall become immediately vested. You
                  will have twelve (12) months (including any trading blackout
                  periods imposed due to insider trading restrictions) after
                  your date of termination of employment to exercise your vested
                  stock options (subject to the option's expiration date as
                  provided in the applicable option agreement).

                  (iv) OUTPLACEMENT SERVICES. You shall receive up to six (6)
                  months of outplacement services at the offices of an
                  outplacement service provider


                                       3
<PAGE>

[NAME]
December [DAY], 2000
Page 4

                  selected by the Company. Such services shall include access to
                  an office, telephone (but not a car phone or mobile phone),
                  e-mail and voice mail. Such services shall cease upon your
                  acceptance of full or part time employment or upon you
                  rendering consulting services on a regular basis.

         Subject to compliance with Section 6(e) and with the exception of
Sections 6(b)(ii) and 6(b)(iv), you shall not be required to mitigate the amount
of any payment or benefit contemplated by this Section 6(b), nor shall any such
payment or benefit be reduced by any earnings or benefits that you may receive
from any other source.

         (c) VOLUNTARY TERMINATION, DEATH OR DISABILITY. In the event you
terminate your employment with the Company of your own volition or as a result
of death or Disability (as defined in the Company's Long-Term Disability Plan),
such termination will have the same consequences as a termination for Cause
under Section 6(a) above.

         (d) RELEASE OF CLAIMS. As a condition to the receipt of the payments
described in this Section 6 and any other post-termination benefits, you shall
be required to execute a release of all claims arising out of your employment or
the termination thereof including, but not limited to, any claim of
discrimination under state or federal law, but excluding claims for
indemnification from the Company under any indemnification agreement with the
Company, its certificate of incorporation and by-laws or applicable law or
claims for directors and officers' insurance coverage.

         (e) OTHER CONDITIONS. The following conditions must also all be
satisfied in order for you to receive (or continue to receive) any of the
payments and benefits provided by this Section 6:

                  (i) Upon the date of your termination of employment, you shall
                  execute the Company's Proprietary Information Agreement
                  Termination Certification (or its successor agreement);

                  (ii) Upon the date of your termination of employment, you
                  shall return to the Company all Company property including,
                  but not limited to, computers, cell phones, pagers, keys,
                  laboratory notebooks, business cards, intellectual property,
                  etc.;

                  (iii) You will fully pay off any outstanding advances, loans
                  or debts owed to the Company no later than their applicable
                  due date or your date of termination of employment (if no
                  other due date has been previously established);

                  (iv) You will submit any outstanding expense reports to the
                  Company within thirty (30) days after the date of your
                  termination of employment;

                                       4
<PAGE>

[NAME]
December [DAY], 2000
Page 5

                  (v) You do not at any time during and subsequent to your
                  period of employment with the Company make any disparaging
                  statements (oral or written) about the Company, or any of its
                  affiliated entities, officers, directors, employees,
                  stockholders, representatives or agents, or any of the
                  Company's products or work-in-progress, in any manner that
                  might be harmful to their businesses, business reputations or
                  personal reputations;

                  (vi) Upon your termination of employment, you will no longer
                  represent that you are an officer or employee of the Company
                  and you will immediately discontinue using your Company
                  mailing address, telephone, facsimile machines, voice mail and
                  e-mail;

                  (vii) You will timely make to the Company any required
                  co-payments needed for the initiation and continuation of
                  post-termination benefits provided to you under this Section
                  6; and

                  (viii) You will disclose to the Company within three (3)
                  business days after the date that you have agreed to accept
                  new full or part time employment or agreed to provide
                  consulting services to another entity or venture.

         (f) OFFSET. Any severance or other payments or benefits made to you
under this Agreement may be reduced, in the Company's discretion, by any amounts
you owe to the Company or as will be needed to satisfy any future co-payments
you would need to make for continuing post-termination benefits.

7. CHANGE IN CONTROL. In the event of a "Change in Control" (as defined under
the Plan), all (100%) of your then-unvested stock options shall become vested
provided that you are employed by the Company on the date of the Change in
Control.

8. EXCISE TAX RESTORATION. In the event that it is determined that any payment
or distribution of any type to or for your benefit made by the Company, by any
of its affiliates, by any person who acquires ownership or effective control or
ownership of a substantial portion of the Company's assets (within the meaning
of section 280G of the Internal Revenue Code of 1986, as amended, and the
regulations thereunder (the "Code")) or by any affiliate of such person, whether
paid or payable or distributed or distributable pursuant to the terms of an
employment agreement or otherwise (the "Total Payments"), would be subject to
the excise tax imposed by section 4999 of the Code or any interest or penalties
with respect to such excise tax (such excise tax, together with any such
interest or penalties, are collectively referred to as the "Excise Tax"), then
you shall be entitled to receive an additional payment (an "Excise Tax
Restoration Payment") in an amount that shall fund the payment by you of any
Excise Tax on the Total Payments as well as all income taxes imposed on the
Excise Tax Restoration Payment, any Excise Tax imposed on the Excise Tax
Restoration Payment and any interest or penalties imposed with respect to taxes
on the Excise Tax Restoration or any Excise Tax.


                                       5
<PAGE>

[NAME]
December [DAY], 2000
Page 6

9. ASSIGNABILITY; BINDING NATURE. Commencing on the Effective Date, this
Agreement will be binding upon you and the Company and your respective
successors, heirs, and assigns. This Agreement may not be assigned by you except
that your rights to compensation and benefits hereunder, subject to the
limitations of this Agreement, may be transferred by will or operation of law.
No rights or obligations of the Company under this Agreement may be assigned or
transferred except by operation of law in the event of a merger or consolidation
in which the Company is not the continuing entity, or the sale or liquidation of
all or substantially all of the assets of the Company provided that the assignee
or transferee is the successor to all or substantially all of the assets of the
Company and assumes the Company's obligations under this Agreement contractually
or as a matter of law. The Company's failure to obtain the successor's
contractual assumption of this Agreement prior to the effectiveness of a
succession shall be a breach of this Agreement and shall entitle you to all the
compensation and benefits to which you would have been entitled if you were
terminated without Cause, on the date such succession became effective.

10. GOVERNING LAW; ARBITRATION. This Agreement will be deemed a contract made
under, and for all purposes shall be construed in accordance with, the laws of
California. Any controversy or claim relating to this Agreement any breach
thereof, and any claims you may have against the Company or any officer,
director or employee of the Company or arising from or relating to your
employment with the Company, will be settled solely and finally by arbitration
in Redwood City, California in accordance with the rules of the American
Arbitration Association ("AAA") then in effect in the State of California, and
judgment upon such award rendered by the arbitrator(s) may be entered in any
court having jurisdiction thereof, provided that this Section 10 shall not be
construed to eliminate or reduce any right you or the Company may otherwise have
to obtain a temporary restraining order or a preliminary or permanent injunction
to enforce the Confidential Information obligations before the matter can be
heard in arbitration. The arbitrator may provide that the cost of the
arbitration (including reasonable legal fees) incurred by you or the Company
will be borne by the non-prevailing party.

11. WITHHOLDING. Anything to the contrary notwithstanding, all payments made by
the Company hereunder to you or your estate or beneficiaries will be subject to
tax withholding pursuant to any applicable laws or regulations. In lieu of
withholding, the Company may, in its sole discretion, accept other provisions
for payment of taxes as required by law, provided it is satisfied that all
requirements of law affecting its responsibilities to withhold such taxes have
been satisfied.

12. ENTIRE AGREEMENT. Except as otherwise specifically provided in this
Agreement, this Agreement contains all the legally binding understandings and
agreements between you and the Company pertaining to the subject matter of this
Agreement and supersedes all such agreements including, but not limited to, any
employment or change of control agreements, whether oral or in writing,
previously entered into between the parties. You also specifically consent to
the immediate termination of any such agreements and waive any and all
provisions contained in such agreements that may have provided for notice
periods with respect to the termination of such agreements or for the
continuation of such agreements beyond their date of termination including the
employment and change of control agreements between the Company

                                       6
<PAGE>

[NAME]
December [DAY], 2000
Page 7

and yourself dated [DATE 1] and [DATE 2], and the additional benefits provided
to you hereunder constitute adequate consideration for your waiver of such
rights.

13. MISCELLANEOUS. No provision of this Agreement may be amended or waived
unless such amendment or waiver is agreed to by you and the Company in writing.
No waiver by you or the Company of the breach of any condition or provision of
this Agreement will be deemed a waiver of a similar or dissimilar provision or
condition at the same or any prior or subsequent time. In the event any portion
of this Agreement is determined to be invalid or unenforceable for any reason,
the remaining portions shall be unaffected thereby and will remain in full force
and effect to the fullest extent permitted by law.

14. INTELLECTUAL PROPERTY.

         (a) GENERAL. Any and all intellectual property (including but not
limited to inventions, trademarks, trade secrets, copyrights, software or
literary creations) made, developed or created by you during the term of this
Agreement using Company time or Company equipment, supplies, facilities,
resources, or trade secret information or which reasonably relate to the
business of the Company or which reasonably relate to any business conducted by
the Company during the term of your employment by the Company (each,
"Intellectual Property"), whether at the request or suggestion of the Company or
otherwise, whether alone or in conjunction with others, and whether during
regular working hours of work or otherwise, shall be promptly and fully
disclosed by you to the Company and shall be the Company's exclusive property as
against you, and you shall promptly deliver to the Company all papers, drawings,
models, data and other material relating to any Intellectual Property made,
developed or created by you as aforesaid. In addition, you covenant and agree to
disclose to the Company any Intellectual Property developed or created by you
during the term of this Agreement, whether or not such Intellectual Property
relates to the business being conducted by the Company at the time of
development or creation of such Intellectual Property.

         (b) WORKS FOR HIRE. You hereby expressly acknowledge and agree that
any copyrights developed or created by you during the term of this Agreement
which reasonably relates to the business of the Company or which reasonably
relates to the business conducted by the Company during your employment by
the Company shall be considered "works made for hire" within the meaning of
the Copyright Act of 1976, as amended (17 U.S.C. Section 101). Each such
copyright as well as all copies of such copyrights in whatever medium fixed
or embodied, shall be owned exclusively by the Company as of the date of
creation.

         (c) COOPERATION. You shall, upon the Company's request and without any
payment therefor, execute all documents necessary or advisable in the opinion of
the Company's counsel to register or protect the Company's Intellectual Property
or to vest in the Company full and exclusive title to such Intellectual
Property, the expense of registering or protecting the Intellectual Property to
be borne by the Company. In addition, you agree not to file any documents
adverse to the Company's ownership of such Intellectual Property.

                                       7
<PAGE>

[NAME]
December [DAY], 2000
Page 8

         (d) DISCLOSURE. This Agreement does not apply to Intellectual Property
that qualifies fully as a nonassignable invention under the provisions of
California law. You hereby covenant and agree to disclose promptly in writing to
the Company all Intellectual Property made or conceived by you during the term
of your employment and for one (1) year thereafter, whether or not you believe
that such Intellectual Property is subject to this Agreement, to permit a
determination by the Company as to whether such Intellectual Property should be
the property of the Company. Any such information will be received in confidence
by the Company.

         If the terms of this Agreement are acceptable to you, please execute
the enclosed copy of this letter and return it to me.

                                Very truly yours,

                                CYGNUS, INC.



                                By:
                                   ---------------------------------------------
                                   John C Hodgman
                                   Chairman, Chief Executive Officer & President

AGREED TO AND ACCEPTED BY:



--------------------------
         [NAME]




                                       8