s7-300 plc a small software

There are 6 setpoint inputs on HMI(between 0-100 %).If conveyor bant speed is lower than 10 m/min then these setpoints must be 30 (% speed) automaticly.If conveyor bant speed is greater than 10 m/min then these setpoints must be loaded with the value coming from the master plc but operator must be change these values.Because sometimes operator needs fine adjust for good production.
Thanks in advance..

Excuse me.I must do a little extra.These setpoints for circulating air fans.If conveyor speed is lower than 10 m/min.then circulating air fan speeds must be 30 (%) automaticly and operator does not change these values because product inside oven can be damaged.Let say conveyor speed is greater than 10 m/min.and operator made fine adjust. Suddenly conveyor stopped.latest value set by the operator must be stored in one place.If conveyor speed is greater than 10 m/min again.latest set values by the operator must be transferred actually setpoints.

Hi Tulip!

If STL is OK for you; here is the simplest I can come up with:
(you ought to have a hysteresis if the speed is fluctuating around 10).

L iConvSpeed
L 10
>I
L iOperatorManipulatedSetpoint
JC _001
L iFixedSetpoint
_001: T iSetpointFanSpeed


Kalle

Hi KalleOlsen for your quick reply.This is okay but perhaps I could not explain you exactly.Let say conveyor speed is greater than 10 m/min.and operator made fine adjust. Suddenly conveyor stopped.latest value set by the operator must be stored in one place.If conveyor speed is greater than 10 m/min again.latest set values by the operator must be transferred actually setpoints.

It is difficult to imagine how your production line looks like. but i interpret this as you need 2 setpoints per conveyor?

Setpoint 1 is the normal speed , > 10.
Setpoint 2 is some kind of startup speed.

At one point during startup, when the actual speed exceeds 10, then Setpoint 1 is to be used.



Have you considered a operating mode change if the conveyor stops? From Auto to Limp / Hand /...


Kalle

Or is the problem to catch the actual value as the conveyor stops?

Kalle

This is a oven has got 6 chambers and circulating air fans.Production is flowing and circulating air fans is cooling chambers.If bant is stop then fans must be operate still for protection of production.conveyor speed exceeds 10 m/min, old 6 circulating air fans setpoints must be transferred to new one.This values are triggered because operator must change these values for good production.

Your information not enough to us imagine,

My guess,


1.) There are 6 set point inputs on HMI (between 0-100 %)

Means each fan has own control,

Whether by analog or communication to control the speed,

2.) Because sometimes operator needs fine adjust for good production

Are this fine adjustment through HMI (main set point 0-100%)? or another set point for only fine adjustment?

Or another guess the fine adjust probably come from fiscal potentiometer then go an analog input PLC.
You need to know for the fine adjustment how many percent you allow from the fan speed ?
You need use comparison, move and add/sub instruction,
The add/sub for fine adjustment only active during conveyor speed low.


Don't mess up your program.

tulip said:

This is a oven has got 6 chambers and circulating air fans.Production is flowing and circulating air fans is cooling chambers.If bant is stop then fans must be operate still for protection of production.conveyor speed exceeds 10 m/min, old 6 circulating air fans setpoints must be transferred to new one.This values are triggered because operator must change these values for good production.

Click to expand...

What is exactly the problem?

Isn't it a simple shift between 2 setpoint sources?

Make a sketch with your setpoints on it.

Our problem is that we see no problem here.

Kalle

I fixed it.Sometimes You see the point, but you can not see anything.Thanks osmanmom and kalleolsen..