I am trying to figure out how to use brewblox to control the flow rate of the pumps using pwm.
I have configured a block ActuatorAnalogInterface which triggers the ActuatorDigitalInterface. However the pump only works when the pwm is 100% if I set it to any value below, the pump just stops working.
Pumps are best used in combination with fast PWM. If you set the PWM period to 100ms, it should correctly correctly trigger variable speed on the pump.
Yeah now it works great 
Thanks
I am testing with the standard HERMS from the Quick Start Wizard but can’t se how can I automate the pumps as well. Is there a way to automatically control the pump for mash recirculation?
It’s HERMS, so I assume you want the pump to be running continuously during the brew steps where you regulate using the HLT. The simplest way to automate this would be to add the PWM to the quick actions enabling/disabling the MT/HLT.
Yes but I was thinking like controlling the pump PWM with some PID as well, for instance when the HLT temperature overshoots the pump slows down or even turns off in order to avoid overshooting in the MT.
The HLT temperature is already indirectly controlled by the MT temperature/setting. If the HLT suffers from overshooting, that’s something best solved in the HLT control chain.
Automatically adjusting the pump for what essentially is a configuration problem is not a reliable solution. Not only does it introduce more configuration (more room for configuration and tuning problems), it will also likely have weird interactions with the MT driving the HLT.
So you would say the best would be to have constant mash flow rate during the mashing and make fine tunings in the HLT / MT control chain if necessary?
Yes. You want the effect of heating the HLT to be as predictable as possible.
Resurrecting this post, what PWM/hardware and configuration did you use to control the flow rate?. looking forward adding this feature using Spark 4.