Matlab, Simulink, which block?

Hi, I've only been using Matlab for a week or so at Uni, so am a complete newbie. As part of my coursework I must create a PID closed-loop control system. The problem I have is; as part of a feedback loop to be created in simulink, the given circuit shows a block with the value (0.5). I've tried using (constant), but get red wires. It needs to have an input wire & output wire. What block should I be using?

Answer 1

[Carla]

Perhaps what you want is the Gain block, with the gain value set to 0.5. This takes an input and multiplies it by 0.5, to output the result.

The Constant block that you tried to use is a source; it doesn't have an input, just an output set to the constant value.

You might also find the PID Controller block of interest.

Answer 2

[Umair Nadeem]

I dont exactly understand what you are trying to say. If you are asking on how to implement a PID then I would say that you would need three blocks. First a constant for P(Proportional), second a derivative block for D and third an integral block for I. The outputs of all these blocks will get added and will connect to the system and provide the feedback. You can easily find these blocks in simulink.

If this doesn't answer your question then please elaborate, it will help.