BASEstar Open DAS
                    for Allen-Bradley Data Highway[TM]
                    on_Tru64[TM]_UNIX[R]________________________________
                    Release Notes

                    Operating System and Version: Tru64 UNIX Version 3.2C

                    Software Version:             Device Access Software
                                                  for Allen-Bradley PLCs,
                                                  Version 3.1



















                    Compaq Computer Corporation
                    Houston, Texas

 






              ________________________________________________________________
              March 2000

              © 1994 Compaq Computer Corporation.

              COMPAQ, VAX and VMS Registered in U.S. Patent and Trademark
              Office.

              BASEstar and OpenVMS are trademarks of Compaq Information
              Technologies Group, L.P. in the United States and/or other
              countries.

              UNIX and The Open Group are registered trademarks of The
              Open Group in the US and/or other countries.

              PLC, PLC-2, PLC-3 and PLC-5 are registered trademarks of
              Allen-Bradley Company Inc.

              PLC-5/250, SLC, SLC 500, SLC 5/01, SLC 5/02, SLC 5/03, SLC
              5/04, SLC 5/05, Data Highway, DH+ and Data Highway Plus are
              trademarks of Allen-Bradley Company, Inc.

              All other products mentioned herein may be trademarks or
              registered trademarks of their respective companies.

              Confidential computer software. Valid license from Compaq
              or authorized sublicensor required for possession, use or
              copying. Consistent with FAR 12.211 and 12.212, Commercial
              Computer Software, Computer Software Documentaion, and
              Technical data for Commercial Items are licensed to
              the U.S. Government under vendor's standard commercial
              license.

              Compaq shall not be liable for technical or editorial
              errors or omissions contained herein. The information in
              this document is subject to change without notice.

              This document was prepared using DECdocument, Version 3.3.

 














     _________________________________________________________________

                                                              Contents



           1     New and Changed Features for 3.1..............      1
           1.1       Increased Timeout for Transactions
                     (V3.1-001)................................      1
           1.2       Self-adjusting Timeout for Transactions
                     (V3.1-002)................................      1
           1.3       New I/O Timeout Error Message
                     (V3.1-002)................................      1
           1.4       Compaq Trademark and Copyright Notices
                     (V3.1A-000)...............................      1
           2     Problems Fixed in This Release................      1
           3     Known Restrictions............................      2
           3.1       Restriction on Devices on a Line..........      2
           4     Known Problems................................      2
           5     Documentation Errata..........................      2




















                                                                   iii

 







        1 New and Changed Features for 3.1

              The following changes are included in this release:

        1.1 Increased Timeout for Transactions (V3.1-001)

              The timeout for a transaction (i.e. the time from sending
              a request to receiving the response from the PLC) has been
              increased. Previously, the timeout value was between 2 and
              3 times the timeout value specified for the device. Now the
              value has been increased to a minimum of 50 seconds and a
              maximum of 60 seconds.

              The transaction timeout was increased to allow for heavily
              loaded systems and/or a slow response from the PLC.

        1.2 Self-adjusting Timeout for Transactions (V3.1-002)

              The timeout for a transaction (i.e. the time from sending
              a request to receiving the response from the PLC) has
              been made self-adjusting. The transaction timeout now is
              calculated by adding five seconds to the maximum of the
              last ten transaction times. The initial transaction timeout
              value is set to the I/O timeout value plus five seconds.

        1.3 New I/O Timeout Error Message (V3.1-002)

              A new error message has been added to log when an I/O
              timeout occurs. Previously, error messages would get logged
              when a transaction timed out or when there was no response
              from the device to a transaction request, but no message
              was logged if a transmission was halted in the middle of
              sending a message.

        1.4 Compaq Trademark and Copyright Notices (V3.1A-000)

              The DAS has been updated to use Compaq standard trademark
              and copyright notices.

        2 Problems Fixed in This Release

              There were no problems fixed in this release.



                                                                        1

 







        3 Known Restrictions

              The following restrictions exist in this release:

        3.1 Restriction on Devices on a Line

              All devices configured on a particular line must be
              accessed using a single process. This restriction exists
              because all devices on a line must share the same physical
              port.

        4 Known Problems

              There are no known problems as of this release.

        5 Documentation Errata

              There are no documentation corrections at this time.



























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