Page 247 - The Art of Designing Embedded Systems

234 THE ART OF DESIGNING EMBEDDED SYSTEMS

before releasing the ECO. (This avoids a formal (and slow) system of
controlled ECO circulation.)
A decision must be made as to how critical the ECO is to production.
The engineer issuing the ECO is authorized to shut down production, if
necessary, to have the ECO incorporated in units currently being built.
Thus, to issue an ECO:
Fill out the ECO form, one per drawing, and distribute it to pro-
duction and all affected engineers.
If you don’t immediately fix the drawing, clip it to the affected
drawing and mark the Master Drawing Book as described.
If necessary, pencil the changes onto the Master drawing.
Increment the Configuration Drawing version number immedi-
ately. Add a line to the Master Drawing Book after the Configura-
tion drawing entry describing the reason for the change, and listing
the affected drawings.
If the change is a mod, consult with production on the proposed
routing of the mod.
If the change is critical, instruct production to incorporate it into
current work-in-progress.
Remember that most likely several drawings will be affected: a
new mod will affect the schematic and the BOM that shows the
mod list.

To incorporate an ECO into a drawing:
Make whatever changes are needed to incorporate ALL ECOs
clipped to that drawing.
Revise the version letter upwards.
Generate a new Master drawing, and Obsolete the old Master.
Delete the ECO file from the network drive.
Revise the Version letter on the Configuration drawing.

Responsi bilities
The engineer making a change is responsible to insure that change is
propagated into the drawing system, and that the information is dissemi-
nated to all parties. He/she is responsible for filing the drawings, removing
and refiling obsoleted drawings, stamping MASTER or OBSOLETE, etc.
The engineer making the change must update production’s master
ROMPAL computer with current programming files, and the drawings
with checksums and versions as appropriate. The engineer must immedi-
ately also update the network drive, and pass out ECOs.