Timer Off Delay Rslogix 5000

[Maitane Roderiques]

The TON, also known as Timer ON, an instruction is used to keep track of time of occurrence of certain events. The conditions preceding the TON instruction will allow the timer to start counting up to a specified value. Once this value is reached, the program will set specific internal bits notifying the programmer as well as other instructions within the PLC that the timer has finished counting. Furthermore, experienced developers can leverage the instruction to know when a certain process is being executed.

An Allen Bradley timer instruction is common to be seen in RSLogix 5, 500, 5000 as well as Studio 5000. A timer is needed in many PLC applications and is used to delay a certain condition. An example of a required timer would be during a startup sequence. As a process is initiated via a "start" push button, each element is started based on a sequence. If there's a way to get the status of these elements, it's possible to avoid using timers. In other words, once an output is set to start a motor, the user may receive feedback that confirms that the motor is running at speed. If such an input is missing, it's possible to issue a timer delay that would assume that the motor is running after a certain time. Example: Once the motor is started, wait 5 second; start the next step.

Click on the question mark above the first contact and type LI01.0 and then press enter. Then click on the question mark above the second contact and type LI01.1 and press enter. Since you already entered descriptions for these bits when you created the I/O mapping, the descriptions will show up above the contacts if it recognizes the tag:

Notice that the right hand side of the branch is highlighted. In order to get the branch to go around the two contacts you just created, click down on the highlighted side of the branch and drag it over to the right side of the two contacts. As soon as you start to drag, small gray rectangles will show up between and around the contacts, and these indicate valid places where you can attach your branch. When you drag it over near the small rectangle on the right side of the contacts, the rectangle will turn into a green oval:

Now select the question mark above the first normally closed contact and type LI01.0 and press enter, and then select the question mark above the second normally closed contact and type LI01.1 and press enter. You now have a completed branch:

Now when these conditions are true, we want to turn on our fault, but only after a short time delay (because we want to ignore the case where the valve is actually changing states). Therefore we need a timer. Start by selecting the right side of the branch:

I was wondering where I could find the completed project link, because the final part of the tutorial is no longer hyperlinked. Any help would be appreciated. I wanted to look at the completed project link to check if these are all sensor faults, or should there be other faults programmed in?

Next, enter the timer preset so that it equals ten seconds. Notice that I typed ten thousand, I did this because the time base of the timer I used is in milliseconds and ten thousand milliseconds equals ten seconds.

Retentive on-delay timers can be used to track the runtime of equipment. They can be set up to trigger an indicator light to let someone know the equipment has run long enough and requires maintenance to inspect and clean it.

SLC 500 Training: In this section we will cover timers used in ladder logic programming. Timers are very important in ladder logic programming. Timers gives the precision in time. Timer on delay starts timing when instruction is true. Timers are used to track time when instruction are on or off. They could also keep track on a retentive base.

This video discusses the basic RSLogix 5000 Allen Bradley PLC Timer instructions. After watching the video, you get the knowledge on how to use Timer on-delay (TON), Timer Off-delay (TOF), Retentive On-delay Timer (RTO) when developing your next PLC program.

FactoryTalk is mentioned quite a bit here, it is a very ambiguous reference as it does not refer to any particular software or hardware. PanelView is also no longer an assumed platform. I assume in this case most often FactoryTalk View ME on a PanelView Plus 6 is what is being compared. A push is not possible on this platform, the project file is replaced over a network and the unit rebooted. With SE an update can be made, but it does not take effect until the applicable screen is reopened.

In any case HMI jogging (any platform) is for machine movements outside of the protected safety zone. Jogging inside the protected area should be performed with a safety dead-man switch in most cases. Or certainly with physical I/O in others. Properly configured local PLC code is also required - the HMI is not what is controlling movements.

Fortunately, we've found that after disabling Push-to-update and changing it to Notify-to-update, as well as putting in some PLC code that uses OTU's with a reset/timer configuration to unlock all buttons after 4 seconds.

Ignoring the safety system issues others have already covered, while the reset timers will indeed fix persistent 'sticky states', 4 seconds is a long time to still be doing potential damage if the button does indeed become stuck again. This is only a bandaid 'solution' applied to dirty skin. IMO, removing all momentary PLC actions from SCADA - where SCADA is setting and resetting PLC values - is a critical step forward. Momentary buttons are a terrible hangover that unfortunately made it into SCADA after hardwired push button panels started being replaced by intelligent HMI/SCADA control systems. This type of jogging action controlled by a SCADA system relying on a comms link is fraught with trouble...

I may be covering ground that has already been covered, but I very rarely if ever us momentary push buttons in any SCADA, HMI application. I am no way an expert but have had experience with Allen Bradley RSLogix 500 / 5000, Panelview Plus, Panel Builder, DTAM's (for those old enough to remember), Omron and the NB / ND screens

Basically I have had some experience with Siemens, AB, Omron, Mitsubishi, Red Lion, Citect, Wonderware and others. In the majority of cases, I use a "Latch" Push Button and turn the bit off within the PLC code. The button is only on for 1 scan. This ensures that if 'communication' is lost between the PLC and the HMI / SCADA, the device will not stay on unless the PLC code allows it. I use this method even when jogging motors etc. The bit is turned on from the screen. it stays on for 1 scan and then it it is reset. If the Push Button is still pressed, it will immediately turn back on for another scan.
This will depend on the scan direction but the Push Button from the screen turns on Bit1 and resets the Push Button then on the line above the "normally Open" of bit1 unlatches / resets Bit1. Bit1 is on for 1 scan cycle and the button is turned off.
I hope I have had a chance to help someone with my method

Writing bits (or anything else) from two directions is inherently racy. After writing, SCADA systems like Ignition expect to see what was written come back on the next polling cycle. There are tweaks to minimize the impact of this (optimistic writes) but they really just open other races.

So, I strongly recommend you NOT set a bit from an HMI and reset that bit in the PLC. At least, not without a relatively long dwell time. That is an anti-pattern. Instead, increment a small integer, letting the change be the equivalent of the pulse from a bit. Keep incrementing (quickly) while the button is pressed. Use a Time-Delay-OFF timer in the PLC with a short timeout to hold the pulse between increments.

In the following demo code I will show a simple example of how to program pulses with different duration of the High (ON) and Low (OFF) states. The demo source codes are shown for Allen Bradley and SIEMENS PLCs, but they are applicable for any industrial controller which can be programmed according to IEC 61131-3.

TON delays a rising signal edge by the time PT. A rising edge at the IN input causes a rising edge at output Q after the time PT has expired. Q then remains set until the IN input changes to 0 again. If the IN input changes to 0 before the time PT has expired, output Q remains set to 0.

TOF delays a falling edge by the time PT. The timer runs only in the STARTUP and RUN modes. A rising edge at the IN input causes a rising edge at output Q. A falling edge at the IN input causes a falling edge at output Q delayed by the time PT.

For one thing the controllers that you can program with this software are very inexpensive. The controllers are the Micro800 series controllers from Rockwell Automation Allen Bradley. And I believe they are all available for less than $1,000.

Many of the controllers come with built-in IO which is another cool feature that saves money and configuration work. so4 smaller automation projects the CCW software and the associated Micro 800 controllers are often a great fit.

One thing that is disappointing about the software is it looks quite a bit different from the rslogix software whether it's Studio 5000 or RSLogix 500 or Micro, all of those software packages have a similar look and feel in the ladder logic.

But regardless this is a great free software package that you can use to not only learn to program plc's on your own time but also to program inexpensive controllers for practice at home or even to control machines and equipment in a plant. The Micro800 controllers are really nice in a lot of ways and can be used alongside or instead of some of the more powerful PLC controllers.

(By the way, if you like videos like this, be sure to check out our membership called myPLCtraining Academy that is full of tutorial and theory style videos to help you become a confident PLC programmer)

Hey guys, Stephen Gates here from my PLC, training.com with another video to help you become a confident PLC programmer. And this week's lesson and video, which we'll continue this theme throughout the month of April, is about connected components workbench and this is a Rockwell automation product and it's a PLC programming package software that is actually free. The standard version is free. And so I thought this would be really useful to a lot of my audience and who are trying to learn PLCs on their own and need some help. I'm working on it on their own time without having to buy expensive software. So I've covered connected components, work bench in another video and introduction to it, how to set up a new project and so on. So I'm going to skip some of that in this video. If you want to learn more about setting up a new project in CCW as we'll call it from now on, there is a link in the description below that will take you to that video.

c80f0f1006