Tagged Questions

Programmable Logic Controller

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2
votes
0answers
60 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 ...
0
votes
2answers
95 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 ...
0
votes
1answer
108 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
votes
2answers
124 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 ...
0
votes
1answer
84 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 ...
2
votes
2answers
163 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 ...
1
vote
1answer
140 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 ...
4
votes
4answers
422 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
votes
1answer
102 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
votes
1answer
103 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 ...
1
vote
1answer
192 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
votes
4answers
248 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) ...
1
vote
3answers
112 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 ...
0
votes
0answers
166 views

Noob needs mac OSX based USB PIC programmer to flash eon EN29LV040A PLCC

Please excuse my ignorance of the more technical issues here. I have a Kurzweil synthesizer which has a corrupt flash chip, which I need to reprogram. I would like to know is what PIC programmer is ...
1
vote
1answer
345 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
votes
1answer
252 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
votes
1answer
855 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 ...
1
vote
2answers
164 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
1answer
261 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 ...
-6
votes
1answer
150 views

What is the name of the control system that is PC based PLC? [closed]

I heard people say that PLC can be replaced by computer based gate logic system and has been used in industries for many years. What is the name of that? Thanks
28
votes
9answers
13k 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 ...