Questions tagged [plc]

Programmable Logic Controller

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29 views

Handling cyclic and acyclic UART messages

I'm looking into designing an IO-Link slave on page 35 of the IO-Link spec they mention Communication Channels. I have received an IO-Link device stack from TEConcept (ST/STM IO-Link partner), I ...
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25 views

Update an Automation Direct PLC Program without DirectSoft?

I tried to find an answer on the internet, buy didn't have any luck searching. I'm fairly new to PLC programming/development (Android/iOS guy, been doing PLC work for the past ~year off and on). I ...
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1answer
69 views

PLC ST programming

I have a mathematical model of two dynamical systems which I need to implement in PLC. But I don't know how to implement differential equations in structured text language. Any suggestions on that ...
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19 views

Connecting PLC with sinking output to PWM analog converter

I am using this pwm converter with this PLC. The PLC digital out is sinking transistor type. I changed the pwm converter jumper switch to 24V and connected +24VDc from PSU to PWM terminal and one of ...
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3answers
55 views

Trigger PLC multiple times with delays

I am brand new to PLC's (don't even have a single device in use yet), but I have been programming for more than 20 years and haven taken classes in electrical controls, so I understand machine logic ...
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1answer
44 views

How to Test Allen Bradley PLC Analog Output Scaling?

I have an Allen Bradley ControlLogix 11756-L72S PLC with a 1734-OE2V 2-Point Analog Output card connected to a SMC pressure regulator that takes a 0-10 V input signal to set the pressure setpoint. I ...
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1answer
32 views

4-20mA PLC analog output ground referencing for other devices

I'm currently using a PLC to control an induction heating coil. I'm using a chinese induction driver that allows 4-20mA PID input. This device runs off standard australian 230v AC 50hz. I've ...
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55 views

Why hasn't the industry standardized sink/source according to sensor/plc component type?

I know quite enough to understand how sink/source works when connecting sensors and PLCs, as well as how it works concerning the electronics components and circuit diagrams. What I don't understand is ...
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2answers
70 views

24V signal to drive led

I have a PLC which gives 24V DC output. I would like to drive an external LED using 24V. Is this the correct way to drive an led? Which is the right method let me know any changes needed. simulate ...
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1answer
120 views

Help me choose the communication protocols that I need

I am developing an industrial sensor using a sensor IC and an ARM MCU which communicate via I2C. The data size is 3 bytes. Because the environment in which the sensor is located is harsh ( high ...
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2answers
61 views

Splitting 0-10V Analog signal from 1 AO to two different set of Ventilators to regulate speed?

Is it possible to take 0-10V signal from analog output and split it in parallel to two different Analog inputs ..to regulate speed of two different sets of ventilators? Or do i need some special ...
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2answers
56 views

How to connect multiple sensors to single PLC input?

Hello. I have a scenario where I have multiple PNP "error signal" from several sensors (let's assume 3 for now). If the sensor output is HIGH, then there is error. If the sensor output is LOW, then ...
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1answer
123 views

In practical, what really is a memory word in PLC?

I came across some plc code (structured text) being used in an industrial company. When I asked the question, I got a blurry answer. However, what I picked up is that it has something to do with the ...
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1answer
44 views

What does the % symbol mean on plc addresses?

I've seen contacts assigned with a % symbol on ladder diagrams and plc structured text. For example a normally open start button would be %I1.02 and a coil would be %Q5.3 I understand the I and Q is ...
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2answers
71 views

Sensor to focus a robot on a welding line. (PLC robotics)

I'm searching for a way to recognize a welding line in an area. When the line is recognized, a small robot needs to follow the line. I searched the web already and spoke with some sensor suppliers. ...
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2answers
72 views

PLC ladder-logic equation stabilization

I have worked with PLCs in the past. Now, I'm working with devices called 'vital-logic controllers'. The vital logic controllers are similar to PLCs, but I'm wondering about a subtlety of how the ...
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29 views

PLC Ladder Logic using LRXSW

I'm working on a project for a summer internship and was hoping for some assistance with PLC Ladder Logic. I have been trying for the last couple of days to program the PLC to do what I want but have ...
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1answer
77 views

How should I match the impedance?

I have a problem for getting the 4-20mA input via 1769-IF8 I/O module. My field device is in good condition, but my AI card doesn’t respond. When I have been browsing about it, most of them said, the ...
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1answer
19 views

Unable to access the module error while trying to simulate a simple PLC Lad program

I am learning PLC and trying to simulate a simple program on Schematic Manager. But I'm having this error that says ...
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1answer
54 views

When using mA on analog devices, does the other wire go to 0V or Earth?

On the Schneider analog input module (link) we have IC, IV, IS, 0V and Earth terminals for a single channel. I've seen people connecting the signal wire from a transducer to the IC terminal and the ...
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2answers
119 views

LED Matrix Light Leakage

I am controlling a 6x6 matrix of LEDs using a PLC with sourcing outputs and sinking outputs (24V). However, there is an issue with current leaking through to other lights. For example, in the ...
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3answers
86 views

Why is there a negative value on the scada when the analog input wire is disconnected from a field instrument?

I'm an apprentice electrician at an fmcg company. I've been seeing a trend recently, at the plant, where the scada actually reads a negative value instead of zero when a field device such as a ...
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1answer
117 views

Legal for trade weighing using a PLC

We have a project where we need to weigh product material for selling to customers. This is a project installed in Europe. This is an industrial product line performing material manufacturing, ...
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1answer
70 views

PLC writing Software [closed]

I wanted to create my own PLC and PLC supporting software. I would like to know how to get started. Is there any software available to create background software? What is a recommended ...
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1answer
67 views

Amplifying Current from 0-20mA to 3A

I would like to drive a pump with a PLC. The PLC generates analog output signal of 0-10V with 0-20mA and the pump runs at the same voltage but 3A current. Is there any solution to this problem? Thank ...
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1answer
79 views

PLC hardware interface for BCD input

I am looking into designing a data converter that must provide data from a Scale (usually referred to as an indicator) to a very old PLC that only accepts data in BCD. The current device that does ...
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2answers
77 views

Measuring accuracy and counting frequency?

The machines at my workshop have meter counters with hall effect sensor switches, which convert shaft rotation to electronic pulses. The switching signal is send to their PLCs' high speed counter ...
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1answer
72 views

PLC s7-1200 Ladder logic

I'm checking some software for PLC s7-1200 According to my knowledge current time will never be > max time. hence, the logic will never trigger [so the code following P_TRIG is useless] ? [I'm ...
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0answers
53 views

What is the fieldbus for Unitronics PLC?

I am currently investigating the inner behavior of a PLC of the brand Unitronics. I identified several bus for the communication with actuators, other PLCs, etc (like Modbus or CANbus) One thing I ...
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2answers
119 views

What is the name of this component

I am a graduate Aerospace Engineering student. I need to wire a pneumatic actuator's controller and a magnetic position sensor for a small part of my research. I received a connection diagram from the ...
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1answer
23 views

Reset variable in another SFC

I am working on a PLC program (using CodeSys) consisting of several SFCs. One SFC is counting rising edges of a button. I want to be able to reset this counter even from anther SFC. How can I do that?
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1answer
93 views

Produce and amplify analog signal with microcontroller (For PLC)

Overview I need to create an analog voltage of 0V-10V for the PLC with a microcontroller with operating voltage 5V. Approach I've been doing this research since last week. I'll share the results of ...
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2answers
76 views

Analog signal exchange between microcontroller and PLC

Overview I need to create an analog voltage of 0V-24V for the PLC ( s7-1200) with a microcontroller with operating voltage 5V. Approach I've been doing this research since yesterday. I'll share ...
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1answer
102 views

24VDC PLC with 12VDC inputs

I have a 24 VDC PLC. It is powered by a power supply that takes in 12 V and turns it into 24 V. This 12 V is coming from a car battery. The inputs for this PLC is 12 V. Here is the smart relay: It ...
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33 views

Media converter - Coax or Twisted Pair [duplicate]

I am working on a Double Leaf Bascule bridge spanning across a river that needs rehabilitated. The bridge is driven from a ControlLogix PLC consisting of 4 racks on the nearside span. Power/control is ...
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1answer
59 views

Cat 5e, any gauge?

I am working on a double leaf bascule bridge and installing a PLC I/O rack on the farside. The power transmission between the two piers (nearside and farside) is via a single submarine cable (...
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2answers
119 views

How to create a Retentive/Accumulative Timer from On-Delay/Off-Delay Timers

According to this post , all timers can be created from just the On-Delay Timer (TON). At the end of the post, after showing how to create an Off-Delay Timer, an On+Off-Delay Timer, and a Flasher ...
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1answer
78 views

Erratic behavior of thermocouple input

I am reading temperature from a K thermocouple on a PLC which is then forwarded to a trending software to see the data on a graph. The thermocouple is in a water trough/reservoir. In fact, there are 3 ...
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2answers
321 views

Best practice for adding Resistor to PLC cabinet

My Micro-step drive and PLC need a simple resistor network between their i/o ports.The optocouplers in the stepper drive have a max input current of 15mA, while the controller needs to output at least ...
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1answer
320 views

How to get ip address Schneider PLC controller TM218LDAE40DRPHN? [closed]

I am new to PLC technology and I am doing the following step, listed below: Connect from PLC to retrieve data through Ethernet using Modbus TCP/IP. I found that PLC didn't have its IP address ...
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1answer
182 views

Using Micrologix 1400 (1766-L32BXB) FET outputs to control frequency input to ST-M5045

There is a minimum current requirement in order to use the FET pins on the Micrologix controller of 21mA, and the output voltage of the pins are 24V. The ST-M5045 stepper driver data sheet says in ...
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1answer
44 views

Can a contactor be used as a temporal logic bit as in PLC?

I want to design a control logic circuit using relay logic. I want to have a bit as a marker as in PLC. Can I use a contactor for this function and then use auxiliary coils as a latch as in PLCs.
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1answer
65 views

How do you set up a VFD to run a motor at 2 different speeds?

I'm already familiar with the concept of altering the frequency to change the speed of the motor. So in this scenario, I'm looking into running a pump at 40Hz (high speed) and 23Hz (low speed). This ...
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1answer
128 views

How to calculate current through a resistor and LED?

Question C asks how's to calculate the current over the led and 3k resistor? Can someone please help me understand how to do it?
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1answer
73 views

Measuring sensor with two PLCs

Can I measure one sensor with two PLCs? I have a PLC that's part of a machine manufacturing stuff. Another PLC is part of a robotic arm that needs to grab the piece. It would be intresting to be ...
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2answers
168 views

Understanding ladder PLC logic

I'm trying to understand the flow logic of ladder language. Is it sequential like C/C++? "i don't think so" Particular case: I've been trying to something very simple but cant make it happen as I ...
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1answer
144 views

How can I connect two mutually exclusive output on one pin of a MCU?

I couldn't be sure how to make a proper headline, correct me if I am wrong with it. I have a reasonably working push button solution including hardware de-bouncing. There is no question on that. So,...
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2answers
223 views

Electrical isolation in PLC output cards

Every output card spec sheet I read says something about electrical isolation. One I read recently said "Isolated 1500VDC channel to channel". What does isolation mean and what advantages do isolated ...
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1answer
81 views

Amplifying milli Volts to Volts

I am currently using a KE-25 oxygen sensor which is galvano microcell type oxygen sensor which doesn't require a power supply to sense oxygen level in the environment. Depending on the concentration ...
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1answer
639 views

Control stepper motor with PLC?

I'm pretty much brand new to both stepper motors and PLC's and electrical in general, although I have an idea of the theory of how they work/what they do. I am trying to achieve is to be able to have ...