Dear Jon and Derek:
I just want to concur with Jon regarding the wisdom of limiting netlist changes to the Viewlogic
environment and limiting the changes made in PADs to ref des renumbering only. We at Amherst Systems have
followed this principal for the past ten years across three different schematic capture package and layout
package configurations. The only time netlist desynchronization problems have arisen have been when
incompatible netlist (connectivity) changes were made concurrently by different people in layout and in
schematic.
If you must delegate schematic capture and layout activities to different parties, at the very least, it
would be wise to keep the single controlled copy of schematics on a LAN-based shared drive. When changes
are required, have the person "check out", that is, cut the controlled copy from the network, and paste it
to his/her local workstation for revision. Only after the schematic returns to the shared drive can
further revisions be made. In this manner, only one official copy of the design is ever editted. Its
absence from the shared drive during editting, signals an engineer needing to revise the design that he has
to either wait or correlate his changes with the party currently editing the design. This "wait state"
adds some sanity to the potentially risky process of concurrent engineering.
Jon R. DeGenova wrote:
> Derek,
>
> One thing I have found to be an absolute necessity is to freeze a copy of
> the schematic after generating the Pads netlist until you are ready for back
> annotation from Pads or need to forward annotate schematic changes while
> layout is in process. What I have found to happen is that while the board
> is in layout, the engineer makes changes to the schematic. If both the Pads
> and Viewlogic netlists have changed, automatic synchronization may become
> nearly impossible. Only change one netlist at a time (either Pads or
> Viewlogic), then synchronize the two before any other changes are made.
>
> We have also found that it is cleaner to make netlist changes in viewlogic
> and forward annotate them to Pads, as opposed to using the Pads ECO
> functions to change any connections. We limit Pads netlist changes to
> resequencing of the reference designators. It also helps to have one person
> who understands both programs in control of the Viewlogic schematic and the
> Pads layout if possible. If the two are controlled by different
> individuals, both must understand how their changes affect the other program
> and keep clear communication throughout the development cycle.
>
> Jon DeGenova
> Micro Industries
>
> > -----Original Message-----
> > From: DesignerCouncil [mailto:[log in to unmask]]On
> > Behalf Of Derek
> > Wynne
> > Sent: Monday, September 14, 1998 6:38 AM
> > To: [log in to unmask]
> > Subject: [DC] ECO Control using PADS & Viewdraw.
> >
> >
> > This message is in MIME format. Since your mail reader does
> > not understand
> > this format, some or all of this message may not be legible.
> >
> > ------ =_NextPart_001_01BDDFCB.BD246E50
> > Content-Type: text/plain;
> > charset="iso-8859-1"
> > Content-Transfer-Encoding: quoted-printable
> >
> > Hi Folks,=20
> >
> > We are having nightmarish problems controlling Eco's while using
> > Viewdraw and PAD's.=20
> > The process is so open to disastrous error by the operator that it has
> > cost us significant=20
> > amounts of time back-tracking to recover files and data. Has anyone =
> > else
> > had experience of the=20
> > interface between these tools and if so what procedures did you use to
> > control the process.=20
> >
> >
> > Thanks in advance.=20
> >
> > Derek=20
> >
> >
> >
> >
> > Derek J. Wynne=20
> > Design Engineer.=20
> > Toucan Technology Ltd.=20
> > I.D.A. Business Park=20
> > Dangan=20
> > Galway City=20
> > Ireland.=20
> > =20
> > Telephone: +35391519913=20
> > Fax: +35391519901=20
> > E-mail: [log in to unmask] < mailto:[log in to unmask]>=20
> > =20
> >
> >
> > ------ =_NextPart_001_01BDDFCB.BD246E50
> > Content-Type: text/html;
> > charset="iso-8859-1"
> > Content-Transfer-Encoding: quoted-printable
> >
> > <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
> > <HTML>
> > <HEAD>
> >
> > <META NAME=3D"Generator" CONTENT=3D"MS Exchange Server version =
> > 5.5.1960.3">
> > <TITLE>ECO Control using PADS & Viewdraw.</TITLE>
> > </HEAD>
> > <BODY>
> >
> > <P><FONT SIZE=3D2>Hi Folks,</FONT>
> > </P>
> >
> > <P><FONT SIZE=3D2>We are having nightmarish problems
> > controlling Eco's =
> > while using Viewdraw and PAD's.</FONT>
> > <BR><FONT SIZE=3D2>The process is so open to disastrous error by the =
> > operator that it has cost us significant </FONT>
> > <BR><FONT SIZE=3D2>amounts of time back-tracking to recover
> > files and =
> > data. Has anyone else had experience of the </FONT>
> > <BR><FONT SIZE=3D2>interface between these tools and if so what =
> > procedures did you use to control the process.</FONT>
> > </P>
> > <BR>
> >
> > <P><FONT SIZE=3D2>Thanks in advance.</FONT>
> > </P>
> >
> > <P><FONT SIZE=3D2>Derek</FONT>
> > </P>
> > <BR>
> > <BR>
> > <BR>
> >
> > <P><FONT SIZE=3D2>Derek J. Wynne</FONT>
> > <BR><FONT SIZE=3D2>Design Engineer.</FONT>
> > <BR><FONT SIZE=3D2>Toucan Technology Ltd.</FONT>
> > <BR><FONT SIZE=3D2>I.D.A. Business Park</FONT>
> > <BR><FONT SIZE=3D2>Dangan</FONT>
> > <BR><FONT SIZE=3D2>Galway City</FONT>
> > <BR><FONT SIZE=3D2>Ireland.</FONT>
> > <BR><FONT SIZE=3D2>=A0</FONT>
> > <BR><FONT SIZE=3D2>Telephone: +35391519913</FONT>
> > <BR><FONT SIZE=3D2>Fax:=A0=A0=A0=A0=A0=A0=A0=A0=A0 +35391519901</FONT>
> > <BR><FONT SIZE=3D2>E-mail:=A0=A0=A0=A0=A0=A0 [log in to unmask] <<A =
> > HREF=3D"mailto:[log in to unmask]" =
> > TARGET=3D"_blank">mailto:[log in to unmask]</A>> </FONT>
> > <BR><FONT SIZE=3D2>=A0</FONT>
> > </P>
> >
> > </BODY>
> > </HTML>
> > ------ =_NextPart_001_01BDDFCB.BD246E50--
>
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Have a Golden Day,
Paul Anderson
[log in to unmask]
http://www.amherst.com/
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