You might get more useful advice if you would describe what you are trying to accomplish that is requiring so many timers. But in the ControlLogix I find it difficult to believe that reusing timers will result in less hassle overall. In a limited PLC where you may need more timers than are available, it can be useful to know how. While it is possible to reuse timers, I don't see any good reasons to do so. One tag per device with all the associated data as members is much easier to manage from a naming point of view.Īdd On Instructions also allow you to embed timers without having to name them separately.īottom line, if naming timers is such a hassle that you are considering reusing them, you are probably doing something the hard way. If the timers are associated with specific types of equipment, consider embedding them in a udt with the rest of the data associated with that type. This allows you to reuse the timer names for common functions and not have to keep coming up with unique names. PRE is exposed outside of the AOI, and Im using less memory and fewer instructions (not that either matter much anymore in modern processors). Timers that are simple delays and do not need to be referenced outside the current program should be declared local. One technique that I use to avoid having to do a MOV of an Input parameter into a timer preset is to make that Input parameter tag an ALIAS of the local Timer tags. It is rare that you need to RES a timer, they are reset when the rung goes false.Īs for the hassle of naming lots of timers, a suggestion: Specifically, check out the instruction help in RSLogix5000 it actually does a fair job of explaining what is going on. You are not clear on how timers work in the PLC. One thing is really clear from your questions so far. There is a wealth of information there with everything I just explained. In RSLogix, click on the timer instruction in your logic window and then press F1. Another hint, and this is going to sound like I am being mean, but that is not my intent. The false timer keeps resetting it.Īs suggested, use a different timer tag for each timer. That is why your other timer is enabling but won't time. Every scan as long as the rung is false, it continues to reset. In other words when the TON timer goes false it really is doing something. a timing diagram for a pulse timer, which generates a pulse with a preset width time. Meaning the instruction does not retain it's data following a power cycle or a false rung. RSLogix 500 provide two time bases (.1 and 1 second). The instruction you are using is categorized as "non-retentive". And continuing that false assumption, since it is not doing anything, you can reuse them elsewhere in your logic. Second method is to create a floating point tag that the HMI accesses, and to scale it and move it into the appropriate timer register. People often think that when a timer or OTE instruction is on a false rung that it is not doing anything. 44 1416 posts Gender: Male North Carolina United States Posted You could select the timer structure.PRE tag and write to it directly, realizing that it's in milliseconds. The timer will be in ON condition as long as the input condition is ON or accumulator value reaches the preset value.This is a common mistake. When Timer receives a positive pulse from the input, it enables and using the timer input contact it enables output coil. Reset coil from bit instructions needs to use separately to reset the timer. This output coil type timer needs one extra input contact (T0) to turn on its output. OFF delay timer coil used for delaying the OFF condition of the output. The Logix Designer application is the rebranding of RSLogix 5000® software and will continue to be the product to program Logix 5000 controllers for discrete, process, batch, motion, safety, and drive -based solutions. This output coil type timer needs one extra input contact (T0) to turn on its output. element is the Studio 5000 Logix Designer® application. ON delay timer coil used for delaying ON condition of the output. ON Delay Timer Coil with Specification.Īs per the below diagram, the upper one (?) is the timer number (T0, T1, T2,….) and the lower one (?) is the timer preset value, the format is S5T#(Preset value in seconds) and its same for all remaining timers.Coil Type Timersĭifferent coil type timers available in PLC, they are Let’s study the working of coil type timers function in Siemens PLC programming.
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