Industrial Control Panels in depth look Part 2: IO
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- เผยแพร่เมื่อ 14 ม.ค. 2018
- Today we are going to be talking in depth about the different types of IO that can be wired into a panel. We will discuss how to actually wire the I/O. We will also show you some steps that are critical to ensure that the devices being wired into the panel are sending and receiving that data as intended.
Let’s first discuss the different signal types that make of the various types of IO in a panel.
Let’s first talk about Digital signals. Digital signals are designed to measure and control a value that is either on, or off. It’s easy to think of this like a common light switch in our home. We can turn it off or off, but we do not have the ability to control how much light we get, or how bright or dark the light is. This is again, how digital signals work. On or off, or True or false, or one or zero. An industrial example of this would be: the status of a motor, it is either running or not running. Or sending a command to start or stop that same motor, we only have two choices, on or off.
Now let’s talk about Analog signals. Analog signals are intended to measure and control a range of values. To better illustrate this point, think of that same light switch. Instead of just turning the light on or off, let’s assume we are using a dimmer switch. The dimmer switch gives us the ability to turn the light on and off, but also allows us to manipulate the light output anywhere in-between the fully on and fully off state of that switch. This is again, how an analog signal works. We measure and control and range of values. An industrial example of this would be: the level in a tank, or the amount of flow or pressure within a pipe.
Now that we have talked about both digital and analog signals, lets discuss how we can use those signals. In these control signals, we have the ability to either send data out, or receive data back to our panel. This data input and output is ultimately what gives that the ability to monitor and control the intended environment.
First-analog inputs
- Analog signals need to be wired with a special kind of wire known as twisted shielded pair.
This kind of wire will have two conductors, as well as a shield wrapped around the wire to protect the signal from any noise or distortion.
It also has a ground wire.
This wire Must be tied to ground within the panel. Not at the instrument.
- Depending on how the instrument is being powered, will determine how you will wire a analog signal. In this case the panel is providing power, which is being sent out to the instrument on this wire.
- The signal that tells the PLC the value you need will come back on the signal wire, and is ultimately tied to the PLC.
Now Analog outputs
- Wired much the same way,.
- We don’t need to supply power in most cases
- Still need to ground the TSP
Digital inputs
- Power is wired to the terminal blocks and sent to the device.
Normally low voltage (24VDC)
- The device will have a set of contacts, that when close will allow power to be brought back to the panel, and ultimately into the PLC.
When the PLC senses this voltage, it reads this as “true”, or “on”
- Normal wire is used
Digital Outputs
- Normal wire is used
- Low voltage signal to a relay
Make sure the coil on the relay matches the output voltage of the PLC
- The coil then switches a higher voltage output signal
Maybe to a motor or solenoid valve
By properly organizing and wiring your IO, you will be able to successfully monitor and control all devices and instruments in the field without any problems.
Additional Links -
Website:
rspsupply.com/
Engineering Page:
rspsupply.com/engineering/
Panel Fabrication Page:
rspsupply.com/panel-fabrication/
Procurement Services Page:
rspsupply.com/procurement-ser...
Manufacturers Page:
rspsupply.com/manufacturers.aspx
PLCs & IO:
rspsupply.com/c-3872-plcs-io....
Relays & Timers:
rspsupply.com/c-1620-relays-t...
Sensors:
rspsupply.com/c-10189-sensors...
Networking & Communication:
rspsupply.com/c-6263-networki...
Cable Wire & Assemblies:
rspsupply.com/c-620-cable-wir... - แนวปฏิบัติและการใช้ชีวิต
I am a civil engineer and have been working water/wastewater construction and design... the electrical and instrumentation part was something I always struggled with.. these videos are treasure... thank you Josh for sharing with us.
Josh, simply brilliant!
Thank you so much for the amazing and very beneficial tutorials!
Thanks for the great video Josh!
This is very detailed!!
RSP, you're the best!
I like your videos, really helpful, but I would like to see more demonstration or just some visualition this way I could understand much more better.
Thank you for this free class Josh bloom 🙌🙏
Cam, thank you for the support!
Can you do a video on MCR and MCP safety circuits?
4:15 the analog input signal examples given were all digital.
Measuring continuous pressure in a pipe or continuous level in a tank would be analog. Measuring anything too high/low would be digital as it would always be too high/low or not too high/low.
cool thing about panel building for a job is its hella hard to have robots do it
Duly Noted
How are the I/O blocks in the bottom part of the industrial cabinet different than the I/O on the PLC?
good, this makes me to enroll for a course
Thanks for watching! We are doing all free education. In the future we will offer courses. Thanks.
thanks remind me
This is better than a course I know I took one
Love the videos. Question for you. In several of your videos you give "typical" locations for things such as IO at the bottom of a panel or main power in at the top of the panel. Are these locations pursuant to some regulation such as NEC of NFPA or UL? Why are they the typical locations?
These locations are not subject to any code you need to follow. They are simply best practices when building control panels. If you were to ask a UL or NEC inspector, they would recommend these locations. Thanks for the feedback. Hope this helps.
My thoughts are that the panel design should be specific to the installation and it may vary on a case by case basis. It does often make sense to have the power near the top as I do think this is usually where people tend to look first. If the power is at the top, you want to find ways to keep power wiring (especially AC) and signal wiring separate in the wire duct. Having the I/O at a different location helps with that. One other important factor to consider with the location of the I/O is that you want the field wiring to easily get from wherever it is brought into to the panel from to the field termination terminal blocks. In a lot of cases, the conduit with field wiring will come up from the bottom (because the conduit was stubbed up from the floor). That makes lower in the panel a natural place for I/O as that is likely where conduit will come in at. However, in many larger panels with large amounts of signal wiring (from instrumentation) much of the panel space may be dedicated to field terminations. In that case it is not unusual for field terminations to take up 50-75% of the panel space. In cases like that the I/O often spans large parts of the cabinet. For example, I/O may make up the entire right half of the cabinet (top to bottom) etc. I think the important thing is for there to be logical separation between areas of the panel and for there to be convenient access to field termination terminal blocks. I also feel that where possible it's nice to have the most frequently accessed parts of the panel at a height that is convenient for people working in the panel but that isn't always possible.
It's also company dependent. For example my company wants all cabinets to have incoming power at top right with the disconnect also being at top right.
I most often made a habit of side or bottom entry in to the enclosure. Especially in areas where there is moisture or potential water contamination. It also seems to help with protection from other contaminants subject to gravity.
Sometimes you just have to go in the top though.
Why does the Analog output not need a power?
Thank you
what is the link to part 1 please? is the basics video?
Would the I/O portion of the panel often be separated into a different marshalling panel? I'm trying to understand the purpose of marshalling panels
Can you please explain each wire conneted in each terminal block
It is just like a wire nut. You have an in and an out.
can you explain the wires connected to terminal blocks in more details
We have a video on that called Wiring Relays
Good video but wiring diagram would clarify things as well as details on one of the analog circuits rather then just pointing at them. Thanks Michael
Excuse me May i have wiring diagram
Some segments in the video are stamped not adjacent to each other
Hi . Can I have wiring from industrial to plc through i/o digital and analogue. Plz
you are god and this channel is heaven
Thank you.