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sensors in Industrial environment

Posted: Tue Dec 04, 2018 5:14 pm
by atulkatti
Hello all
I want to deploy some IOT applications in an industrial environment. TO connect sensors to the Pi what type of cables should I use so that I can avoid noise and these should also be long enough (eg 1/2 meters)
Atul

Re: sensors in Industrial environment

Posted: Tue Dec 04, 2018 5:42 pm
by scotty101
Totally depends on the type of sensor and the protocol over which they communicate with the Pi.

You'll need to provide more details.

Re: sensors in Industrial environment

Posted: Wed Dec 05, 2018 3:51 am
by atulkatti
I have temperature , proximity, load and ultrasonic level sensor which will feed data to the pi. from the pi i will stream data via ethernet cable and also operate a relay to turn an AC motor on/off. Not sure whats the best protocol to use I2C, Serial or UART

Re: sensors in Industrial environment

Posted: Wed Dec 05, 2018 10:19 am
by atulkatti
Im planning to use LM35 and DS18B20 for temperature sensing.
For proximity im searching for a sensor that can detect the end of a roll (edge detection) (DC 6-36V Inductive 4mm PNP-NO ??)

WHat type of cables can be used to carry data from these sensors to Pi in a industrial environment which is usually dry ?

Re: sensors in Industrial environment

Posted: Wed Dec 05, 2018 10:58 am
by Brandon92
First of all, lets talk about safety because it is a industrial environment. What happend when the AC motor can't be turned on or off? (or the Rpi doens't response any more)

And for the wire you need a good shielded cable and also the designed connectors for that cable that connect to the same shield at both ends. (When you don't connect the shield to the ground at both ends. You might as well use the cheapest cable.)

And direct communication that comes out of the Rpi to the cable is also not a good idea. For example, if you need to use I2C. You need one of this solutions: The same story also applies to other communication protocol.

*first part-number I could find.

Re: sensors in Industrial environment

Posted: Fri Dec 07, 2018 8:06 am
by atulkatti
What would be a good temperature sensor with range between 0 to 250C , compatible with the PI in industrial environment, running 24 X 7

Re: sensors in Industrial environment

Posted: Fri Dec 07, 2018 9:54 am
by Brandon92
A PT100 is also a sensor that is used in a industrial environment.

Re: sensors in Industrial environment

Posted: Fri Dec 07, 2018 5:53 pm
by atulkatti
my requirement is to insert a temp sensor in a MS heating pad. The temperature range is 0 to 250. Not sure if LM35 /DS18B20 can serve the purpose. But it needs to be long lasting and reliable. one requirement is that if the temp goes below a set temp, then we need to turn off a motor. so the reading needs to be precise and instantaneous

Re: sensors in Industrial environment

Posted: Fri Dec 07, 2018 6:25 pm
by Brandon92
The sensor that you are talking about will "melt" at that temperature range. And are no good. This sound like a important process and if something happends with the Rpi, you have problem.

And that is why I would advice you to use a off the shelf solution. Then you know for sure it works and it is tested. As a example, I didn't read the datasheet!

https://uk.rs-online.com/mobile/p/on-of ... s/7983450/

Re: sensors in Industrial environment

Posted: Sun Dec 09, 2018 4:38 pm
by atulkatti
i think best option is to have thermocouple or RTD

Re: sensors in Industrial environment

Posted: Sun Dec 09, 2018 5:05 pm
by atulkatti
ok ...any advise on the selection of pressure and photoelectric sensors (PE)? need PE to detect the end of a plastic roll

Re: sensors in Industrial environment

Posted: Sun Dec 09, 2018 6:01 pm
by Brandon92
Okay, first of all.
What is the goal of this project:
  • To monitor a current machine, without touching the original control circuit/ machine
  • The Rpi will control the entire machine in a industrial environment

And some more background of this project would also be helpful.
atulkatti wrote:
Sun Dec 09, 2018 5:05 pm
ok ...any advise on the selection of pressure and photoelectric sensors (PE)? need PE to detect the end of a plastic roll
As an example, the pressure sensor: does it need to wight a mass of: 0.1g, 1g, 1kg, 100kg, 1000kg, ...

Re: sensors in Industrial environment

Posted: Mon Dec 10, 2018 4:54 am
by atulkatti
The goal of this project is to use sensors like temp sensor, pressure sensor and photoelectric sensors to control a motor (still not very clear on the specs on the motor. But a relay will do this job based on output of the Pi). The pressure sensor have a max force of 10 kg)

Re: sensors in Industrial environment

Posted: Mon Dec 10, 2018 6:54 am
by Brandon92
atulkatti wrote:
Mon Dec 10, 2018 4:54 am
The goal of this project is to use sensors like temp sensor, pressure sensor and photoelectric sensors to control a motor (still not very clear on the specs on the motor. But a relay will do this job based on output of the Pi). The pressure sensor have a max force of 10 kg)
Well in that case. You can not use a Rpi to control a machine. And especially not in a industrial environment. Because you can not predic how the pi would fail in all the conditions.

You need in this case a dedicated PLC. This device is designed for controlling a machine in a industrial environment.
And if you need to be qualified for this task. I would advise you to hire someone that is qualified to do this, if you aren't qualified. Because the machine, code, electronic, ect.. need to be according to a legal and safetie standaard. In the case that something goes wrong, nobody gets hurt and nothing goed up in flames.

Re: sensors in Industrial environment

Posted: Mon Dec 10, 2018 9:35 am
by atulkatti
so instead of interfacing the PI with the motor, can i interface it with PLC for turning motor on/Off. We currently have a PLC but its not too intelligent.

Re: sensors in Industrial environment

Posted: Mon Dec 10, 2018 9:17 pm
by Brandon92
First of all, I'm not a expert on this topic so.
atulkatti wrote: so instead of interfacing the PI with the motor, can i interface it with PLC for turning motor on/Off. We currently have a PLC but its not too intelligent.
That is also not correct. The PLC need to control everything. As an example what happend if you don't. You set the temperature to 250C. And all the sensors are connected to the Rpi. And the Rpi drive the PLC (motor). The Rpi decide to turn on/off* the motor. And an x amount of time the Rpi crashes, dies, restart, ect. And your motor stays in that last state forever. Because the PLC sees that his input is still high/low*, and doesn't know the other imported parameters to drive the motor.

If a PLC controls everything, you can program it in such a way, or buy specials parts, that it is always in a safe state is something goes wrong. Here is a nice document. And also here.

And yes, this is not a easy task if you are not familiar with it. However, like I said before. If you don't have the knowledge about this subject**, hire someone that does have the right knowledge about his topic and also knows how it is legally structured in your country. I can not give you all the information, because I don't have all the information about your project and the topic.

*what ever is the worst case for safety
** I think you don't have the correct knowledge about this topic, based on the questions you are asking.

Re: sensors in Industrial environment

Posted: Tue Dec 11, 2018 6:15 am
by atulkatti
acknowledge and appreciate your feedback. Thanks