Programmable Logic Controller

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62 views

Writing long PLC code routine without scan-time over-run

I wonder if is a problem with response time of PLC in some cases? If so, what is the case? How to designer it solves ? For example calculation are to complex, the next step must be calculated in 200 ...
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1answer
70 views

Ladder Logic for PLC Program

Having trouble understanding this ladder logic program. I can solve more basic ladder logic programs but I do not know how to account for small voltage adjustments. Here is the problem: You are ...
-1
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3answers
71 views

interchangeable operation of two electric motors without PLC

I have two motors that drive an air compressor. I have a pressure switch to turn the motors on/off. The sequence I want is: when pressure switch turns ON - motor 1 starts, when pressure switch ...
-1
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2answers
52 views

Turning LED lights on/off based through any wireless means

I've spent several hours researching this website for an answer to my question. The problem is i don't know the terminology or anything. So if you know the answer please treat me as an individual with ...
0
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1answer
70 views

Timers and counters

I have to build a ladder diagram for a system which sounds the alarm if inside 60 seconds after pressing the start button,10 objects have passed.The alarm goes on until we press stop.In the system we ...
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0answers
53 views

Broadcast traffic issue in PLC Ethernet network

The setting: network with about 10 PCs and 8 AB RSLogix 5000 PLCs. The issue: Everything is communicating OK, but I'm seeing what appears to be a lot of broadcast traffic within the network. It is ...
0
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2answers
86 views

Updating outputs in PLCs

For all PLC manufacturers, is Mass I/O copying the choice for updating outputs? I found that there is another possible method: the continuous I/O updating. Can anyone tell me what is the reason for ...
2
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4answers
151 views

PLC rung definition and evaluation

I was reading a book about PLCs (Programmable Logic Controllers). I found this paragraph: "A ladder diagram is read from left to right and from top to bottom... The top rung is read from left to ...
3
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3answers
188 views

Industrializing a PIC micro-controller

I want to replace some timers with a PIC16F887 micro-controller. The problem is that the input voltages to the I/Os is going to be 24V which is too much. For the output part I was thinking about using ...
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2answers
171 views

Opto Coupler output voltage drop when connected to PLC

I have an input of pulse width 5 ms and which is fed to a Buffer IC and then the output of the buffer is FED to an opto isolator whose collector is pulled with a pull up of 7.5k resistor with an 24 V ...
3
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3answers
352 views

Connect Arduino to Omron PLC

I work at a manufacturing plant (in software engineering) and we have 3rd party hardware and software that monitors industrial machinery (primarily speeds). For training and testing we need to be ...
0
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1answer
71 views

Is this something a P.L.C. would be able to do?

I wish to replace the zener diodes with a programmable chip, so that I can program the chip to do exactly what the zener diodes do in this circuit. This will then make the circuit universal to all my ...
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1answer
152 views

Decoding coax signal

There is an old age board (doubt to be a PLC) which outputs keypad and touch panel data through a single BNC connector. I've managed to capture its output signal using oscope which is available in ...
4
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1answer
217 views

SSI to RS485 communication protocol

How do I interface a positioning sensor with SSI interface with an OMRON safety PLC with only RS485 interface? I understand both are serial, but would I loose resolution if I interface it?
0
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1answer
239 views

How can computer replace PLC in industrial machines? [closed]

I am having internship in a semiconductor manufacturing company and learning about machines in front-end section. Technicians say that the machines all use computers as they process multiple complex ...
4
votes
1answer
220 views

Technical term for this kind of PLC I/O?

I don't claim to be an electrical engineer or even an electrician as I work with software more often than hardware, my job does however often work with panel wiring and wiring I/O; I was hoping ...
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2answers
175 views

PLC with or without PC

I heard from a colleague that typical PLC serve as an interface between a the signals and, for want of a better word, a PC. The connection, being typically done with ethernet, and the PC runs some ...
2
votes
1answer
2k views

Max232 giving incorrect values at pins

Background: I'm trying to connect a Compact Logix PLC -> MAX232CPE Maxium chip -> arduino. Currently my PLC does communicate modbus RS232 with a request for data from the arduino. I can see this by ...
0
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1answer
459 views

Ladder diagram, variation of Latch and Lock

I have a problem for expanding this particular ladder diagram. The cylinder is a double acting pneumatic cylinder type. START -> Start button A+ and B+ -> Cylinder moving forward A- and B- -> ...
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2answers
65 views

plc not reading photo eye

I recently changed a photo eye and it's all wired and on functioning property but when it comes to the plc it's not changing the status on the input card? What is causing this problem?
2
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4answers
681 views

How to detect stuck relay in PLC?

Is there a standard method of detecting a stuck relay in PLC? Say, I want to build a H-bridge using relays: simulate this circuit – Schematic created using CircuitLab In case one of the ...
-1
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1answer
669 views

Stepper motor control using siemens s71200 plc [closed]

I am doing a project in which i want to run a conveyor belt using a stepper motor, through a siemens s71200 plc.Can anyone help me in doing so.
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2answers
986 views

Interfacing Arduino and Siemen's PLC S71200

I am doing a basic project relating to home automation in which i want to glow an LED/Bulb using a PLC wirelessly. A BLE module DBM01-S is used which takes signals from an Android phone and transfers ...
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2answers
213 views

ADC using S7 1200

I have a project on temperature control system using s7 1200,my analogue input temperature range is 0 to 100 degree centigrade and thermocouple sensor gives 10mV per degree centigrade,do i need to ...
2
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0answers
66 views

Load cells for 4 legged beer fermenter [duplicate]

I'm a homebrewer. I use 5, 4 legged 200 liter tanks to ferment the beer. I would love to be able to weigh the tanks and have the signal on my PLC to see how much I have in the tanks. Each tank ...
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3answers
242 views

Pictures of different adapters, trying to understand how they work (PLC to PC communication)

I purchased the blue adapter in the picture as a USB/RS232 converter. It takes in the RJ12 cable from my PLC, and converts it to a USB input. Now when I try to use an RJ12-DB9 Female and then connect ...
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2answers
966 views

Can I transmit data over RJ12 to a PC from a PLC?

I have a Click PLC which has two RJ12 ports. I have successfully programmed it using C# and nModBus as a slave, but now I want to test the PLC as a master and the PC as a slave and noticed my laptop ...
4
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2answers
520 views

Isolating an analogue input using ADC/DAC

I'm looking into isolating an analogue input coming from field equipment and interfacing to a PLC analogue input module. The input will be of the 4-20mA range (1-5V). There are a few ways to approach ...
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1answer
241 views

SMD Code Parts BE P04 & AE P04

I'm looking to find out what these parts are on a PLC controller. Both are SOT-89 packages. The AE P04 I suspect maybe something to do with a constant current circuit for +24vDC for a 4-20mA loop ...
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2answers
596 views

Solenoid stays on when output turned off

I have a power supply with 12V running into a the common on my PLC. Output 0 on the PLC is wired into a solenoid. The negative on the solenoid runs into the ground on the power supply completing the ...
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1answer
428 views

Monitoring a fan with 2800 RPM with a Siemens 27-226 PLC

I have a fan that rotates at 2800 RPM. I need to make sure that the fan is operating. I need to monitor the fan. It has an output that gives a signal 2 times per rotation so it's 5600 pulses which is ...
5
votes
5answers
1k views

Digital logic input with very wide input voltage range

We are developing an industrial controls product that will be used to monitor the presence or absence of voltage ranging from 5V to 480V. Since the unit will be generic and programmable, this input ...
2
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1answer
246 views

How to work out or calculate this circuit?

I'm not an engineer, I understand a lot but I fail to understand how it works and how to calculate this for a 24vdc input:
2
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1answer
165 views

When is a programmable logical controller the best choice? [duplicate]

I am studying PLCs as a part of my Elements of Industrial Automation class. Trouble is, I can't imagine why would anyone use such a thing. For complex tasks, microcontrollers are available. The vast ...
3
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1answer
772 views

Voltage detection / Universal uC Input => CLD, PTC

I'm currently developing a open-source "Home-PLC" for home automation. Every thing runs fine so far and I have a module with fixed voltage AC inputs and outputs. In the next step I want the build '...
2
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4answers
430 views

250 LED control

I am in the process of designing an automated rock climbing wall that will have 250 monocolor LEDs lit in a predetermined pattern that will be changing every 10 seconds. My controller (actually a PLC) ...
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3answers
280 views

Noise on Proximity switch signal on PLC system

I am working on a PLC based system that uses High Speed counter cards to pick up a signal from a 24 VDC proximity switch. I am having a problem with short duration 10 to 15 volt spikes being seen on ...
1
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1answer
744 views

PLC to act as or simulate 4-20 mA transducer

I have a PLC Control system that measures a few 4-20 mA pressure sensors. Today we test these with loop calibrators on each channel. I want to set up a PLC that simulates these pressure sensors so I ...
0
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1answer
350 views

How to stop two DC motors simultaneously using limit switches

I need some help - I'm building a machine but I'm not sure of the best way of doing it. Thanks a million for your help Just to refresh my point - I've made one or two changes I have two large wire ...
2
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1answer
3k views

How to find electrical conductivity from frequency in my PLC project

I am using a 555 timer which is supposed to measure the electrical conductivity of milk. Here's a circuit for a conductivity sensor: It provides the needed isolation, uses AC measurement, and the ...
2
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3answers
371 views

What does a PLC read if I have an unconnected input?

What does a PLC read if I have an unconnected input? I know that I can test it, but I want to know whether there is any default ?
0
votes
2answers
537 views

How does a safety PLC work?

I have read the manual, but I am not sure how the omron safety PLC works. I guess this safety PLC use Output Power Supply Output (21,22) to drive the output circuit, but why does it need (1,2) the ...
36
votes
14answers
32k views

Why use PLC instead of microcontroller?

Why does everyone use PLCs in industrial environments, instead of a microcontroller based solution? For a longer task, the PLC program is as complicated as a microcontroller program. A ...