Don,
I seriously doubt ladder logic is going away very soon...
There has been a lot of work on developing new programming
methodologies such as IEC 61131-3 with ladder, sequential function
charts, and structured text, but in most customer sites your basic
ladder logic is prefered by the maintenance personel as they are
familiar with it. Indeed the car industry limits which instructions
you can use to ensure as common a programming methodology as possible.
Your example below does not take into account the potential for many
things to be happening concurrently with interlocks which are common
in production line systems.
My current project consists of multiple sets of four servo drives
programmed in a form of multi-taskinng Basic, each monitored by a
7300 with encoder inputs. The overall control and sequencing of the
systems - and also the interface to the customers production line
equipment is via an Allen Bradley PLC programmed in Ladder logic.
Regards,
PJE
--- In ts-7000%40yahoogroups.com, "Don W. Carr" <> wrote:
>
> I was kind of hoping that Ladder Logic would die a slow death, but
it seems
> there are always engineers that want to keep propagating it. What
we really
> need is a simple real-time script language, with object tags, kind
of like
> this:
>
> valve1.open
> pid1.setpoint(200)
> wait_until(temp > 100)
> burner.send(50)
> data_aquisition1.start
> delay(10)
> data_aquisition1.stop
>
> It would be a whole lot easier to teach to scientists or other non
> programmers. You could even make a web interface that lived on a
7xxx to
> allow them to enter the scripts, and also set the tagnames of the
AI, DI,
> AO, DO, and the engineering units, alarms, etc.
>
> I will have this eventually, but I have too many projects right
now. It is
> actually all there, I just need to port it to the 7xxx and clean up
some
> loose ends.
>
> Another interesting programming method is state charts, which I
also plan to
> add to my control engine.
>
> Well, as much as we might wish it, ladder logic will NOT go away.
>
> Don.