Document:

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                                                                   EXHIBIT 10.50

                            OPTION ESCROW AGREEMENT

     THIS OPTION ESCROW AGREEMENT (the "Agreement") is made effective as of the
Effective Time (as defined in the Merger Agreement (as defined below)) by and
among Industrial Data Systems Corporation, a Nevada corporation ("Parent"), PEI
Acquisition, Inc., a Texas corporation, all of whose capital stock is owned
(indirectly through ownership of IDS Engineering Management, LC, a Texas
limited liability company) by Parent (the "Purchaser"), the persons and
entities listed on the attached Schedule 1 (the "Significant PEI
Shareholders"), Michael L. Burrow, acting as the shareholder representative for
the Significant PEI Shareholders (the "Shareholder Representative"), and Johnny
J. Williams (the "Escrow Agent").

                                   RECITALS:
                                   --------
     A.   Parent, Purchaser, IDS Engineering Management, LC, a Texas limited
liability company, and Petrocon Engineering Inc., a Texas corporation ("PEI"),
entered into a Merger Agreement on or about July 31, 2001 (the "Merger
Agreement").

     B.   The Merger Agreement provides that each outstanding and unexercised
PEI stock option and warrant that represents a right to acquire securities in
PEI shall be assumed by Parent and converted into an option or warrant, as the
case may be (together, the "Surviving Options"), to purchase shares of Parent
common stock, par value $.001 per share (the "Common Stock"), in an amount and
at an exercise price set forth in the Merger Agreement.

     C.   The Merger Agreement further provides that the Significant PEI
Shareholders are to deposit the number of shares of Common Stock equal to the
number of shares issuable on the exercise of the Surviving Options (the "Escrow
Shares"), into an escrow created by this Agreement, which shall be a fund to
satisfy the obligations under the Surviving Options pursuant to the Merger
Agreement.

     D.   Pursuant to the terms of the Merger Agreement, upon the exercise of
any Surviving Option, the Parent shall deliver the aggregate exercise price
(less any amount required to be paid in by Parent for social security and
Medicare taxes as a result of such exercise) received by Parent (the
"Consideration") to the Escrow Agent for deposit into an escrow created by this
Agreement.

     E.   This Agreement, together with the Merger Agreement, shall govern the
terms upon which Escrow Agent may distribute the Escrow Shares to holders of
the Surviving Options (the "Surviving Option Holders") and to the Significant
PEI Shareholders. Capitalized terms used in this Agreement but not defined
herein shall have the definition ascribed to them in the Merger Agreement.

     NOW, THEREFORE, in consideration of the promises contained herein and in
the Merger Agreement and other good and valuable consideration, the receipt of
which is hereby acknowledged, the parties hereto agree as follows:

                                      1
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                                  AGREEMENT:

     1.   Appointment of Escrow Agent; Delivery of Escrow Shares; Delivery of
          -------------------------------------------------------------------
Exercise Price. Each of the Parent, Purchaser, and the Shareholder
--------------
Representative hereby appoints Johnny J. Williams as Escrow Agent, and Escrow
Agent hereby accepts such appointment. Immediately after the Closing, the
Shareholder Representative shall deliver or cause to be delivered to Escrow
Agent original share certificates registered in the name of the Shareholder
Representative as agent for the Significant PEI Shareholders, and representing
the Escrow Shares, together with a fully executed blank stock power bearing the
name of Escrow Agent as the transferee. Upon the exercise of any Surviving
Option after the Closing, the Parent shall deliver the Consideration to the
Escrow Agent.

     2.   Parent's Claim Certificates. Parent, from time to time on or prior to
          ---------------------------
the expiration of the Surviving Options, may make a claim to some or all of the
Escrow Shares (the "Parent's Claim") by delivering to Escrow Agent a
certificate (the "Parent's Claim Certificate") signed by the president or a
vice president of Parent stating:

          (a)  That a Surviving Option Holder has exercised a Surviving Option;

          (b)  The amount of Consideration received by Parent from the
Surviving Option Holder, and that such Consideration has been delivered to the
Escrow Agent;

          (c)  The amount of the Parent's Claim (rounded to the nearest whole
share), which shall be a number of Escrow Shares equal to the number of shares
issuable upon the exercise of the Surviving Option;

          (d)  That, upon payment of the Parent's Claim, the Parent shall
cancel a number of Escrow Shares equal to the amount of the Parent's Claim; and

          (e)  That Parent has delivered a copy of such Parent's Claim
Certificate to the Shareholder Representative and the date on which such
copy was delivered.

     3.   Disputed Parent's Claims. The Shareholder Representative may dispute
          ------------------------
or object to any Parent's Claim, in whole or in part, by delivering to Escrow
Agent a notice (a "Shareholder Representative's Objection Notice") within 15
days of receipt of the Parent's Claim Certificate stating:

          (a)  That the Shareholder Representative disputes or objects to such
Parent's Claim;

          (b)  The reasons for such objections or dispute, set forth in
reasonable detail;

          (c)  That the Shareholder Representative has delivered a copy of the
Shareholder Representative's Objection Notice to Parent and the date on which
such copy was delivered; and

          (d)  The portion of the Parent's Claim set forth in the Parent's Claim
Certificate, if any, which is not disputed or objected to.

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     Whenever there shall be delivered to Escrow Agent a Shareholder
Representative's Objection Notice, Parent and the parties shall invoke the
conciliation and arbitration procedures set forth in the Merger Agreement. Any
claim which is disputed or objected to by the Shareholder Representative shall,
to the extent of such dispute or objection, constitute a "Disputed Claim."

     4.   Distribution of Escrow Shares.
          -----------------------------

          (a)  If Escrow Agent receives from the Shareholder Representative
written notice of consent or agreement to all or part of a Parent's Claim, or
fails to receive a timely Shareholder Representative's Objection Notice, Escrow
Agent shall thereupon promptly:

               (1)  deliver to Parent from the Escrow Shares a share
certificate or certificates representing a number of shares equal to the amount
of such Parent's Claim.

               (2)  deliver the Consideration to each Significant PEI
Shareholder based on their Pro Rata Share (as hereinafter defined); provided
however that if any Significant PEI Shareholder's Pro Rata Share of the
Consideration is less than $500, the Escrow Agent may hold such funds in escrow,
in a non-interest bearing account, until the amount of the disbursements due to
such Significant PEI Shareholders aggregate at least $500.

          (b)  If the Escrow Shares are not sufficient to satisfy in full any
obligations to Parent under the preceding Section 4(a), Escrow Agent shall
deliver to Parent such Escrow Shares as are available.

     5.   Shareholder Representative's Claim Certificates. The Shareholder
          -----------------------------------------------
Representative, upon the expiration of any Surviving Options, may make a claim
to some or all of the Escrow Shares (the "Shareholder Representative's Claim")
by delivering to Escrow Agent a certificate (the "Shareholder Representative's
Claim Certificate") signed by the Shareholder Representative stating:

          (a)  That a Surviving Option has expired;

          (b)  The amount of the Shareholder Representative's Claim (rounded
to the nearest whole share), which shall be a number of Escrow Shares equal to
the number of shares that would otherwise have been issued upon exercise of the
expired Surviving Option; and

          (c)  That the Shareholder Representative has delivered a copy of
such Shareholder Representative's Claim Certificate to the Parent and the date
on which such copy was delivered.

     6.   Disputed Shareholder Representative's Claim. The Parent may dispute
          -------------------------------------------
or object to any Shareholder Representative's Claim, in whole or in part, by
delivering to Escrow Agent a notice signed by the president or vice president
of the Parent (a "Parent's Objection Notice") within 30 days of receipt of the
Shareholder Representative's Claim stating:

          (a)  That the Parent disputes or objects to such Shareholder
Representative's Claim;

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          (b)  The reasons for such objections or dispute, set forth in
reasonable detail;

          (c)  That the Parent has delivered a copy of said Objection Notice to
the Shareholder Representative and the date on which such copy was delivered;
and;

          (d)  The portion of the Shareholder Representative's Claim set forth
in the Shareholder Representative's Claim Certificate, if any, which is not
disputed or objected to.

     7.   Payment of Shareholder Representative's Claims.
          ----------------------------------------------

          (a)  If Escrow Agent receives from the Parent written notice of
consent or agreement to all or part of a Shareholder Representative's Claim, or
fails to receive a timely Parent's Objection Notice, Escrow Agent shall
thereupon promptly deliver to the Significant PEI Shareholders the number of
shares equal to their Pro Rata Share (as hereinafter defined); provided however
that if any Significant PEI Shareholder's Pro Rata Share of such shares is less
than 500 shares, the Escrow Agent may hold such shares in escrow until the
aggregate number of undisbursed shares attributable to such Significant PEI
Shareholders' Pro Rata Share (together with any other undisbursed shares
attributable to such Significant PEI Shareholder's Pro Rata Share) is 500 or
more shares.

          (b)   If the Escrow Shares are not sufficient to pay in full any
amounts payable to the Significant PEI Shareholders under Section 7(a), Escrow
Agent shall pay to Significant PEI Shareholders such Escrow Shares as are
available.

     8.   Distribution of Escrow Shares.
          -----------------------------

          (a)  Escrow Agent shall not make any distribution of Escrow Shares
with respect to any Parent's Claim or Shareholder Representative's Claim until:

              (1)  it receives the written consent or agreement of the Parent or
the Shareholder Representative, as the case may be, with respect to such
distribution, or fails to receive a timely Shareholder Representative's
Objection Notice or Parent's Objection Notice; or

              (2)  there is a Final Decision with respect to a Disputed Claim.
"Final Decision" means a decision, order, judgment or decree of an arbitrator or
court having jurisdiction which is either not subject to appeal or as to which
notice of appeal has not been timely filed or served.

          (b)  In addition to the foregoing, Parent, Purchaser, Escrow Agent and
the Shareholder Representative agree that at any time and from time to time,
Parent shall be authorized, upon the joint written request of the Shareholder
Representative and a Surviving Option Holder and within five days of such
request, to issue to such Surviving Option Holder the number of shares of Common
Stock specified by the Shareholder Representative and such Surviving Option
Holder (which number may be zero) in such request (the "Requested Shares"),
provided that contemporaneous with such written request:
          --------

              (1)  the Surviving Option is thereby canceled;

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              (2)  the Escrow Agent surrenders to Parent for cancellation a
number of shares of Common Stock equal to the number of shares that the
Shareholder Representative and such Surviving Option Holder have requested
Parent to issue in such request;

              (3)  the number of Escrow Shares remaining would be equal to or
greater than the aggregate number of shares issuable upon exercise of all then
outstanding Surviving Options.

          (c)  Promptly following the issuance of any Requested Shares, the
Escrow Agent shall issue to the Significant PEI Shareholders the number of
Escrow Shares equal to the difference between the total number of shares
issuable upon the exercise of the Surviving Option canceled in connection with
the issuance of the Requested Shares (regardless of whether such shares were
vested) and the number of Requested Shares.

     9.   Adjustments to Escrow Shares; Dividends; Voting.
          -----------------------------------------------

          (a)  If Parent or any Significant PEI Shareholder is entitled to
receive any securities or other distributions in respect of or in exchange for
any of the Escrow Shares (other than dividends declared by the Board of
Directors of Parent on the Escrow Shares that are payable in cash), whether by
way of stock dividends, share splits, recapitalizations, liquidations, mergers,
consolidations, split-ups, spin-offs, redemptions, exchanges or conversions of
shares and the like ("New Shares"), such Significant PEI Shareholder shall
deliver share certificates representing such New Shares and such other
distributions (registered in the name of the Shareholder Representative as agent
for such Significant PEI Shareholder) to Escrow Agent, along with a fully
executed blank stock power bearing the name of the Escrow Agent as the
transferee. Upon receipt of such New Shares and other distributions, Escrow
Agent shall hold in escrow such securities and the same shall be subject to all
of the provisions of this Agreement relating to the Escrow Shares.
Notwithstanding anything to the contrary herein, any dividend declared by the
Board of Directors of Parent that is payable in cash with respect to the Escrow
Shares shall not be delivered to the Escrow Agent and each Significant PEI
Shareholder shall be entitled to receive such Significant PEI Shareholder's Pro
Rata Share of such cash dividend.

          (b)  Subject to the terms of the Voting Agreement, the Shareholder
Representative shall have all voting rights with respect to the Escrow Shares
for so long as such Escrow Shares are held in the Escrow Fund; provided that if
                                                               --------
so directed by the Requisite Shareholders (as hereinafter defined) with respect
to any matter submitted to a vote of the shareholders of IDS, the Shareholder
Representative shall, subject to the Voting Agreement, vote the Escrow Shares
as directed by the Requisite Shareholders. "Requisite Shareholders" means, on
any date of determination, Significant PEI Shareholders having a Pro Rata Share
of 51% or more of the Escrow Shares.

     10.   Distributions and Reductions. With respect to any distribution of the
           ----------------------------
Escrow Shares to the Significant PEI Shareholders, each Significant PEI
Shareholder shall be entitled to receive such Significant PEI Shareholders' Pro
Rata Share of the Escrow Shares, and with respect to any delivery of Escrow
Shares to the Parent in accordance with the terms hereof each Significant PEI
Shareholder shall bear its Pro Rata Share of such reduction in the Escrow
Shares. Each Significant PEI Shareholder's Pro Rata Share shall be the
percentage set forth in Exhibit 1.
                        ---------

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     11.   Shareholder Representative as Agent.
           -----------------------------------

          (a)  Appointment. Each Significant PEI Shareholder hereby designates
               -----------
and appoints the Shareholder Representative as its Shareholder Representative
and agent under this Agreement, and each Significant PEI Shareholder hereby
irrevocably authorizes Shareholder Representative to execute and deliver the
documents and to take such action or to refrain from taking such action on its
behalf under the provisions of this Agreement and to exercise such powers as
are set forth herein or therein, together with such other powers as are
reasonably incidental thereto. In performing its functions and duties under
this Agreement, Shareholder Representative shall act solely as agent of the
Significant PEI Shareholders and does not assume and shall not be deemed to
have assumed any obligation toward or relationship of agency or trust with or
for Parent or Purchaser.

          (b)  Nature of Duties. The duties of the Shareholder Representative
               ----------------
shall be mechanical and administrative in nature. The Shareholder Representative
shall not have by reason of this Agreement a fiduciary relationship in respect
of any Significant PEI Shareholder. Nothing in this Agreement, express or
implied, is intended to or shall be construed to impose upon Shareholder
Representative any obligations in respect of this Agreement except as expressly
set forth herein or therein. If Shareholder Representative seeks the consent or
approval of any Significant PEI Shareholder to the taking or refraining from
taking any action hereunder, then Shareholder Representative shall send notice
thereof to each Significant PEI Shareholder. Shareholder Representative shall
promptly notify each Significant PEI Shareholder any time that the Requisite
Shareholders have instructed Shareholder Representative to act or refrain from
acting pursuant hereto.

          (c)  Rights, Exculpation, Etc. Neither Shareholder Representative
               ------------------------
nor any of his agents shall be liable to any Significant PEI Shareholder for
any action taken or omitted by them hereunder or under the Merger Agreement, or
in connection herewith or therewith, except that Shareholder Representative
shall be liable to the extent of its own gross negligence or willful misconduct
as determined by a court of competent jurisdiction. Shareholder Representative
may at any time request instructions from the Significant PEI Shareholders with
respect to any actions or approvals which by the terms of this Agreement,
Shareholder Representative is permitted or required to take or to grant, and if
such instructions are promptly requested, Shareholder Representative shall be
absolutely entitled to refrain from taking any action or to withhold any
approval and shall not be under any liability whatsoever to any person or
entity for refraining from any action or withholding any approval under this
Agreement until it shall have received such instructions from Requisite
Shareholders or all or such other portion of the Significant PEI Shareholders
as shall be prescribed by this Agreement. Without limiting the foregoing, no
Significant PEI Shareholder shall have any right of action whatsoever against
Shareholder Representative as a result of Shareholder Representative acting or
refraining from acting under this Agreement in accordance with the instructions
of Requisite Shareholders and, notwithstanding the instructions of Requisite
Shareholders, the Shareholder Representative shall have no obligation to take
any action if it believes, in good faith, that such action exposes Shareholder
Representative to any liability for which it has not received satisfactory
indemnification in accordance with Section 11(d).

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          (d)  Indemnification. Significant PEI Shareholders will reimburse
               ---------------
and indemnify Shareholder Representative for and against any and all
liabilities, obligations, losses, damages, penalties, actions, judgments, suits,
costs, expenses (including, without limitation, reasonable attorneys' fees and
expenses), advances or disbursements of any kind or nature whatsoever which may
be imposed on, incurred by, or asserted against Shareholder Representative in
any way relating to or arising out of this Agreement or any action taken or
omitted by Shareholder Representative under this Agreement, in proportion to
each Significant PEI Shareholders' Pro Rata Share, but only to the extent that
any of the foregoing is not reimbursed by Parent or Purchaser; provided,
                                                               --------
however, that no Significant PEI Shareholders shall be liable for any portion of
-------
such liabilities, obligations, losses, damages, penalties, actions, judgments,
suits, costs, expenses, advances or disbursements to the extent resulting from
Shareholder Representative's gross negligence or willful misconduct as
determined by a court of competent jurisdiction. If any indemnity furnished to
Shareholder Representative for any purpose shall, in the opinion of Shareholder
Representative, be insufficient or become impaired, Shareholder Representative
may call for additional indemnity and cease, or not commence, to do the acts
indemnified against even if so directed by Requisite Shareholders until such
additional indemnity is furnished. The obligations of the Significant PEI
Shareholders under this 11(d) shall survive the termination of this Agreement.

          (e)  Successor Shareholder Representative.
               ------------------------------------

              (1)  Resignation. Shareholder Representative may resign from
                   -----------
the performance of all its agency functions and duties hereunder at any time by
giving at least 30 days prior written notice to the Significant PEI
Shareholders. Such resignation shall take effect upon the acceptance by a
successor Shareholder Representative of appointment pursuant to Section 11(e)(2)
or as otherwise provided below.

              (2)  Appointment of Successor. Upon any such notice of resignation
                   ------------------------
pursuant to Section 11(e)(1) above or the death or disability of the Shareholder
Representative, Requisite Shareholders shall appoint a successor Shareholder
Representative. If, with respect to a retiring Shareholder Representative, a
successor Shareholder Representative shall not have been so appointed within the
30-day period referred to in Section 11(e)(1), the retiring Shareholder
Representative, upon notice to the Escrow Agent, may petition any court of
competent jurisdiction to appoint a successor escrow agent.

              (3)  Successor Shareholder Representative. Upon the acceptance
                   ------------------------------------
of any appointment as Shareholder Representative under the Agreement by a
successor Shareholder Representative, such successor Shareholder Representative
shall thereupon succeed to and become vested with all the rights, powers,
privileges and duties of the retiring Shareholder Representative, and the
retiring Shareholder Representative shall be discharged from its duties and
obligations under this Agreement. After any retiring Shareholder
Representative's resignation as Shareholder Representative or upon the death or
disability of the Shareholder Representative, the provisions of this Section
11(e)(3) shall inure to its benefit as to any actions taken or omitted to be
taken by it while it was Shareholder Representative.

     12.   Share Certificates. In connection with any issuance of Escrow Shares
           ------------------
to Parent or to any Significant PEI Shareholder, Escrow Agent and Parent agree
to take any and all actions

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necessary to cause a stock certificate evidencing the number of shares to be
delivered to Parent, delivered to the Significant PEI Shareholders or to Escrow
Agent, as the case may be, as required or specified in this Agreement,
including the issuance of stock certificates to each Significant PEI
Shareholder evidencing the Pro Rata Share of such Significant PEI Shareholder
with respect to any distribution to the Significant PEI Shareholders required
by this Agreement.

     13.   Notices.  All notices (including Objection Notices), certificates
           -------
(including Parent's Claim Certificates and Shareholder Claim Certificates),
payment, and distributions required or permitted to be given or delivered
hereunder shall be deemed to have been properly given or delivered to the
following addresses, if delivered in person, or, if mailed, on the second
business day following the date when mailed by registered or certified mail,
postage prepaid and addressed as follows:

  If to Purchaser:                        PEI Acquisition, Inc.
                                          Attn: William A. Coskey
                                          600 Century Plaza Drive, Building 140
                                          Houston, Texas 77073

  With a copy (which shall not
  constitute notice) to:                  Jenkens & Gilchrist
                                          A Professional Corporation
                                          Attn: Kathryn K. Lindauer
                                          600 Congress Avenue, Suite 2200
                                          Austin, Texas 78701

  If to Parent:                           Industrial Data Systems Corporation
                                          Attn: William A. Coskey
                                          600 Century Plaza Drive, Building 140
                                          Houston, Texas 77073

  With a copy (which shall not
  constitute notice) to:                  Jenkens & Gilchrist
                                          A Professional Corporation
                                          Attn: Kathryn K. Lindauer
                                          600 Congress Avenue, Suite 2200
                                          Austin, Texas 78701

  If to Shareholder Representative:       Mr. Michael L. Burrow
                                          3155 Executive Blvd.
                                          Beaumont, Texas 77705

  With a copy (which shall not
  constitute notice) to:                  Gardere Wynne Sewell LLP
                                          Attn: Gary B. Clark
                                          1601 Elm Street, Suite 3000
                                          Dallas, Texas 75201

                                      8
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  If to Escrow Agent:                     Johnny J. Williams
                                          13831 Northwest Freeway, Suite 155
                                          Houston, Texas  77040

or to such other address as a party shall designate by written notice to all
other parties to the Agreement.

     14.   Escrow Agent.
           ------------

          (a)  Reliance. The Escrow Agent may act upon any instrument or other
               --------
writing believed by it in good faith to be genuine and to be signed or presented
by the proper person or persons and shall not be liable in connection with the
performance by it of its duties pursuant to the provisions hereof, except for
its own willful misconduct or gross negligence. Parent, Purchaser, and each
Significant PEI Shareholder shall, jointly and severally, indemnify and hold
harmless the Escrow Agent pursuant to Section 17 of the Agreement.

          (b)  Successor Agent.
               ---------------

              (1)  Resignation. Escrow Agent may resign from the performance
                   -----------
of all its agency functions and duties hereunder at any time by giving at least
30 days prior written notice to Parent and the Shareholder Representative. Such
resignation shall take effect upon the acceptance by a successor Escrow Agent
of appointment pursuant to Section 14(b)(2) or as otherwise provided below.

              (2)  Appointment of Successor. Upon any such notice of
                   ------------------------
resignation pursuant to Section 14(b)(1) or the death or disability of the
Escrow Agent, Parent and the Shareholder Representative shall, by mutual
agreement, appoint a successor Escrow Agent. If, with respect to a retiring
Escrow Agent, a successor Escrow Agent shall not have been so appointed within
the 30 day period referred to in Section 14(b)(1), the retiring Escrow Agent,
upon notice to Parent and the Shareholder Representative, may petition any
court of competent jurisdiction to appoint a successor Escrow Agent. The
retiring Escrow Agent shall continue to serve until his successor is duly
appointed and accepts such service.

              (3)  Successor Escrow Agent. Upon the acceptance of any
                   ----------------------
appointment as Escrow Agent under the Agreement by a successor Escrow Agent,
such successor Escrow Agent shall thereupon succeed to and become vested with
all the rights, powers, privileges and duties of the retiring Escrow Agent, and
the retiring Escrow Agent shall be discharged from its duties and obligations
under this Agreement. After any retiring Escrow Agent's resignation as Escrow
Agent or upon the death or disability of the Escrow Agent, the provisions of
this Section 14(b)(3) shall inure to its benefit as to any actions taken or
omitted to be taken by him while he was Escrow Agent.

     15.  Termination of Escrow. Upon the expiration, termination or
          ---------------------
cancellation of all Surviving Options, the Escrow Shares and any Consideration
received with respect thereto held by Escrow Agent pursuant to the terms of
this Agreement, less a reasonable reserve (as determined by mutual agreement of
Parent and the Shareholder Representative, but if they cannot agree, then by
the Escrow Agent) to cover Disputed Claims shall be distributed by

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Escrow Agent to the Significant PEI Shareholders or their respective successors
or assigns. With respect to Shares reserved to cover Disputed Claims, upon
settlement of such Disputed Claim, this escrow shall terminate, and all
remaining Escrow Shares held by Escrow Agent shall be distributed by Escrow
Agent to the Significant PEI Shareholders.

     16.  Fees and Expenses. The Escrow Agent shall not be entitled to
          -----------------
compensation for his services. The Escrow Agent shall be reasonably compensated
for services and reimbursed for all costs and expenses, including reasonable
attorney's fees and expenses, occasioned by any delay, controversy, litigation
or event, and the same shall be recoverable one-half from the Significant PEI
Shareholders (with each Significant PEI Shareholder being responsible for its
Pro Rata Share of such one-half) and one-half from Purchaser.

     17.  Indemnification of Escrow Agent. Parent, Purchaser, and each
          -------------------------------
Significant PEI Shareholder hereby agrees to jointly and severally indemnify
and hold harmless Escrow Agent from and against, any and all loss, liability,
cost, damage and expense, including, without limitation, reasonable counsel
fees, which Escrow Agent may suffer or incur by reason of any action, claim or
proceeding brought against Escrow Agent arising out of or relating in any way
to this Agreement or any transaction to which this Agreement relates unless
such action, claim or proceeding is the result of the willful misconduct or
gross negligence of Escrow Agent. Escrow Agent may consult counsel in respect
of any question arising under this Agreement or the Merger Agreement, and
Escrow Agent shall not be liable for any action taken or omitted in good faith
upon advice of such counsel. The Significant PEI Shareholders' portion of any
indemnity pursuant to this Agreement shall be deducted from the Escrow Shares.

     18.  Resignation of Escrow Agent. Escrow Agent may resign upon 30 days
          ---------------------------
advance written notice to the Shareholder Representative, Parent, and
Purchaser. If a successor escrow agent is not appointed within the 30-day
period following such notice, Escrow Agent may petition any court of competent
jurisdiction to name a successor escrow agent.

     19.  Counterparts. This Agreement may be executed by facsimile and in two
          ------------
or more counterparts, each of which shall be deemed an original and all of which
taken together shall constitute one agreement. Signatures transmitted via
facsimile shall be deemed originals for purposes of this Agreement.

     20.  Governing Law. This Agreement shall be construed, performed, and
          -------------
enforced in accordance with, and governed by, the internal laws of the State of
Texas, without giving effect to the principles of conflict of laws thereof that
direct the application of the laws of a different state. Venue for any disputes
pursuant to this Agreement shall be in Harris County, Texas, and the parties
agree to submit to the jurisdiction of the state and federal courts in Harris
county, Texas.

     21.  Amendments. This Agreement may be amended or modified, and any of the
          ----------
terms, covenants, representations, warranties, or conditions hereof may be
waived, only by a written instrument executed by the parties hereto, or in the
case of a waiver, by the party waiving compliance. Any waiver by any party of
any condition, or of the breach of any provision, term, covenant,
representation, or warranty contained in this Agreement, in any one or more
instances, shall not be deemed to be nor construed as further or continuing
waiver of any such conditions,

                                      10
<PAGE>

or of the breach of any other provision, term, covenant, representation, or
warranty of this Agreement.

     22.  Section Headings. The section headings in this Agreement are for
          ----------------
reference purposes only and shall not affect the meaning or interpretation of
this Agreement.

     23.  Severability. If any provision of this Agreement is held by final
          ------------
judgment of a court of competent jurisdiction to be invalid, illegal or
unenforceable, such invalid, illegal or unenforceable provision shall be severed
from the remainder of this Agreement, and the remainder of this Agreement shall
be enforced. In addition, the invalid, illegal or unenforceable provision shall
be deemed to be automatically modified, and, as so modified, to be included in
this Agreement, such modification being made to the minimum extent necessary to
render the provision valid, legal and enforceable. Notwithstanding the
foregoing, however, if the severed or modified provision concerns all or a
portion of the essential consideration to be delivered under this Agreement by
one party to the other, the remaining provisions of this Agreement shall also be
modified to the extent necessary to equitably adjust the parties' respective
rights and obligations hereunder.

            [The Remainder of this Page is Intentionally Left Blank]

                                      11
<PAGE>

     IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
signed the day and year first above written.

                                  PETROCON ENGINEERING, INC.

                                  By:_________________________________
                                     Michael L. Burrow, President and Chief
                                     Executive Officer

                                  INDUSTRIAL DATA SYSTEMS CORPORATION

                                  By:_________________________________
                                     William A. Coskey, President

                                  PEI ACQUISITION, INC.

                                  By:_________________________________
                                     William A. Coskey, President

                                  SHAREHOLDER REPRESENTATIVE

                                  _________________________________
                                  Michael L. Burrow

                                  ESCROW AGENT

                                  _________________________________
                                  Johnny J. Williams, Esq.

                    Signature Page to Option Escrow Agreement
<PAGE>

                               SIGNIFICANT PEI SHAREHOLDERS:

                               EQUUS II INCORPORATED,  a  Delaware
                               corporation

                               By:
                                  _________________________________
                                  Randall B. Hale, Vice President

                               M.L. Burrow Family Partnership, Ltd.*
                               Michael L. Burrow*
                               Fahad Al-Tamimi*
                               Norbert C. Roobaert*
                               David L. Hopson*
                               Jimmie N. Carpenter*
                               Thomas H. Noble*
                               Douglas W. Eckols Family Partnership, Ltd.*
                               The Olan Weeks Family Limited Partnership, Ltd.*
                               Olan B. Weeks*
                               Terry D. Allen*
                               Lowell J. Walker, Sr.*
                               Mills Group, Ltd.*
                               Robert W. Raiford*
                               Robert G. Chapman Family Partnership, Ltd.*
                               Owen G. Vaughn, Jr.*
                               The   Lawrence   J.   Bradford   Family
                               Partnership, Ltd.*
                               Robert A. Knost*
                               David Smith*
                               William or Carolyn Miller*
                               Willie E. Rigsby*
                               Byron P. Walker, Sr.*

*    Indicates that the Shareholder has executed this Option Escrow Agreement
     by execution of a Master Signature Page.

                   Signature Page to Option Escrow Agreement
<PAGE>

                                   SCHEDULE 1

                          SIGNIFICANT PEI SHAREHOLDERS
                          ----------------------------

             Name                                    Pro Rata Share
             ----                                    --------------

M.L. Burrow Family Partnership, Ltd.                      10.759%
Michael L. Burrow                                          8.967%
Equus II Incorporated                                     13.208%
Fahad Al-Tamimi                                            9.051%
Norbert C. Roobaert                                        8.627%
David L. Hopson                                            7.780%
Jimmie N. Carpenter                                        4.766%
Thomas H. Noble                                            3.830%
Douglas W. Eckols Family Partnership, Ltd.                 3.666%
The Olan Weeks Family Limited Partnership, Ltd.            3.370%
Olan B. Weeks                                              1.628%
Terry D. Allen                                             3.346%
Lowell J. Walker, Sr.                                      2.803%
Mills Group, Ltd.                                          2.298%
Robert W. Raiford                                          2.162%
Robert G. Chapman Family Partnership, Ltd.                 2.073%
Owen G. Vaughn, Jr.                                        2.036%
The Lawrence J. Bradford Family Partnership, Ltd.          2.022%
Robert A. Knost                                            1.755%
David Smith                                                1.594%
William or Carolyn Miller                                  1.460%
Willie E. Rigsby                                           1.628%
Byron P. Walker, Sr.                                       1.169%<PAGE>

                                                                   EXHIBIT 10.51

                        Name:______________________________________________

                                     Lock-Up Agreement Form

December 21, 2001

Industrial Data Systems Corporation
600 Century Plaza Drive
Suite 140
Houston, Texas 77073-6013

            Re:       Industrial Data Systems Corporation (the "Company")

Ladies and Gentlemen:

         The undersigned is an owner of record or beneficially of certain shares
of common stock of Petrocon Engineering, Inc. ("PEI Common Stock") or
securities convertible into or exchangeable or exercisable for the PEI Common
Stock. Petrocon Engineering, Inc. ("PEI") proposes to enter into a merger
whereby PEI Acquisition, Inc., a wholly owned, indirect subsidiary of the
Company, will merge with and into PEI (the "Merger") with PEI as the surviving
corporation. As consideration for their PEI Common Stock and securities
convertible into or exchangeable or exercisable for the PEI Common Stock, each
of the shareholders of PEI will receive shares of common stock, par value $.001
per share, of the Company ("Company Common Stock") and/or securities
convertible into or exchangeable or exercisable for Company Common Stock
("Company Options" and together with Company Common Stock, "Securities"). The
undersigned recognizes that the Merger will be of benefit to the undersigned
and will benefit PEI and the Company. The undersigned acknowledges that the
Company is relying on the representations and agreements of the undersigned
contained in this letter in closing the Merger and in issuing Company Common
Stock to the undersigned in connection with the Merger.

In consideration of the foregoing, the undersigned hereby agrees that the
undersigned will not offer to sell, contract to sell, or otherwise sell,
dispose of, loan, pledge or grant any rights with respect to (collectively,
a "Disposition") any shares of Company Common Stock, any options or warrants to
purchase any shares of Company Common Stock or any securities convertible into
or exchangeable or exercisable for shares of Company Common Stock
(collectively, "Securities") now owned or hereafter acquired directly by such
person or with respect to which such person has or hereafter acquires the power
of disposition, otherwise than (i) as a bona fide gift or gifts, provided the
donee or donees thereof agree in writing to be bound by this restriction, (ii)
as a distribution to partners, beneficiaries or shareholders of such person,
provided that the distributees thereof agree in writing to be bound by the
terms of this restriction, (iii) with respect to sales or purchases of
Securities acquired on the open market, (iv) with respect to sales or purchases
of Securities between the undersigned and any other person who is subject to a
lockup agreement which is essentially identical to this Lockup Agreement, (v) as
a contribution by the undersigned to any escrow account established pursuant to
the terms of the Merger or any
<PAGE>

distribution by the escrow agent of any Securities to the undersigned or the
Company pursuant to the terms of the agreements governing such escrow accounts,
or (vi) with the prior written consent of the Company, which may be granted or
withheld in the sole discretion of the Company. In addition, notwithstanding
the foregoing, if the undersigned is a corporation, partnership or trust, the
corporation, partnership or trust may transfer Securities to any affiliate of
such corporation, partnership or trust and if the undersigned is an individual,
such individual may transfer such Securities by gift, will or intestacy to a
member or members of his or her immediate family, or to a trust or partnership,
the beneficiaries or partners of which are exclusively the undersigned and/or a
member or members of his or her immediate family; provided, however, that in
                                                  --------  -------
such case it shall be a condition to the transfer that the transferee execute
an agreement stating that the transferee is receiving and holding such
Securities subject to the provisions of this Lock-Up Agreement, and provided
further that such transfer not involve a disposition for value. For purposes of
this Lock-Up Agreement, "immediate family" shall mean any relationship by
blood, marriage or adoption, not more remote than first cousins. The foregoing
restrictions will terminate upon the earlier of (i) a Sale of the Company, or
(ii) the close of trading of the Company Common Stock on the second anniversary
of (and including) the day of the Merger (the "Lock-Up Period"). "Sale of
                                                                  -------
Company" shall mean (i) a sale of substantially all of the assets of Company to
-------
a person or entity that is not an affiliate of Company, (ii) any sale in a
single transaction or in a series of related and substantially similar
contemporaneous transactions of the Company Common Stock, representing 50% or
more of the total number of shares of Company Common Stock then outstanding
(determined on a fully diluted basis) to any person or entity which is not an
affiliate of the selling shareholders, or (iii) any merger, consolidation or
reorganization of the Company with or into one or more entities which are not
Subsidiaries or affiliates of the Company, as a result of which less than 50%
of the outstanding voting securities or partnership interests of the surviving
or resulting entity are, or are to be, owned by the holders of Company Common
Stock immediately prior to such merger, consolidation or reorganization. The
foregoing restriction has been expressly agreed upon to preclude the holder of
the Securities from engaging in any hedging or other transaction which is
designed to or reasonably expected to lead to or result in a disposition of
Securities subject to this Lock-Up Agreement during the Lock-Up Period, even if
such Securities would be disposed of by someone other than such holder. Such
prohibited hedging or other transactions would include, without limitation, any
short sale (whether or not against the box) or any purchase, sale or grant of
any right (including, without limitation, any put or call option) with respect
to any Securities or with respect to any security (other than a broad-based
market basket or index) that includes, relates to or derives any significant
part of its value from the Securities. The foregoing restrictions do not,
however, preclude any exercise of a warrant or options to purchase Company
Common Stock during the Lock-Up Period or the disposition of any Securities
which are not subject to this Lock-Up Agreement. The undersigned also agrees
and consents to the entry of stop transfer instructions with the Company's
transfer agent and registrar against the transfer of Securities subject to this
Lock-Up Agreement except in compliance with the foregoing restrictions.

     The undersigned hereby agrees that the certificate or certificates
evidencing the Securities subject to this agreement shall, for the duration of
the Lock-Up Period, have the following legend:
<PAGE>

          THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO
          A CONTRACTUAL RESTRICTION ON TRANSFER AND MAY NOT BE SOLD,
          PLEDGED, HYPOTHECATED OR OTHERWISE TRANSFERRED EXCEPT AS
          SET FORTH IN THAT CERTAIN LOCKUP AGREEMENT BETWEEN THE
          COMPANY AND THE HOLDER HEREOF, A COPY OF WHICH IS ON FILE
          AT THE PRINCIPAL OFFICES OF THE COMPANY

          Notwithstanding the foregoing, the legend set forth
above shall, at the request of the holder, be removed from the certificate or
certificates evidencing the Securities released from this Lock-Up Agreement
upon the termination of the Lock-Up Period. This agreement is irrevocable and
will be binding on the undersigned and the respective successors, heirs,
personal representatives, and assigns of the undersigned. Nothing in this
Lock-Up Agreement shall constitute an offer by the Company to sell, or create
any right or obligation for the undersigned to purchase any Securities. In the
event the Merger has not occurred on or before December 31, 2001, this Lock-Up
Agreement shall be of no further force or effect.

                                     Date: December 21, 2001

                                     _________________________________________*

*          Indicates that the Shareholder has executed this Lock-Up Agreement by
execution of a Master Signature Page.

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