A watchdog is a piece of code that will timeout when an error occurs in our program. It will usually cause the CPU (program/sketch) to stop or reset.
We will now look at the instructions for the watchdog timer in productivity blocks. This includes the Configure Watchdog, Start Watchdog, Stop Watchdog, and Pet Watchdog.
Our sample sketch will modify the P1000 Expansion Digital Inputs and Outputs Part 2 program by adding a watchdog timer.
Let’s get started. Continue Reading!
Time instructions in our productivity blocks programming (Arduino sketches) consist of runtime (ms), runtime (us), delay ms, and delay microseconds us.
We will be looking at each of these instructions that are available for our program using productivity blocks. Delay instructions in our sketches should be used with caution. They will pause our program for the delayed time, not allowing other parts of the program to function. We will be looking at this and the method to do the exact same delay functions without pausing your program.
A sample program will be discussed to demonstrate the time functions in our program. Let’s get started. Continue Reading!
Timers are present in just about every PLC program that I have seen. A timing chart is the secret behind understanding of the timer that you need in your application. Making a timing chart before writing the program will ensure that all of the information will be accounted. The secret to using timers is a good review of using these timing charts.
PLC Fiddle has three different timing instructions for us to use in our programs. On-Delay, Off-Delay and Retentive Timers. We will discuss the timer parameters and the three different instructions. Our timer challenges will help you gain a good understanding of how timers work in the PLC. Let’s get started. Continue Reading!
Just about every programmable logic controller (PLC) program will include a timer instruction. The Productivity 1000 Series PLC has several different timer instructions for your program. We discussed the timed coil (TMC) and flasher coil (FLS) last time as part of the contacts and coil discussion. (Contact and Coil Instructions – Video)
We will now look at using the Simple Timer (STMR) and the Timer (TMR) instructions in the productivity suite software. Let’s get started. Continue Reading!
A majority of the programmable logic controller (PLC) programs will include a timer instruction. The BRX series of programmable logic controllers have several different timers available for your program. There are nine different basic timing instructions in the PLC. The memory area for timers, include the Timer PVs (Present Values) Timer SVs (Set Values) and the Timer Completion Flags. The default size of the timer area is T0 – T255. This size can change to the amount that we need for our program. Please see BRX PLC Numbering Systems and Addressing on how to change the memory configuration of the controller.
We will be looking at the timer instructions in the BRX PLC along with some programming examples. As a system integrator, this ability can prove very useful to you in the field when commissioning your automation system. When dealing with timers, we need to look at timing charts. The Secret of Using Timers is a good refresher on using timing charts.
Let’s get started with the BRX PLC Timers. Continue Reading!
The Omron CP1H series of programmable logic controllers are capable of having 4096 timers. There are twelve different timing instructions in the PLC. Six binary and six BCD instructions for the set values of the timers separate the six basic instructions. The memory area for timers has separate areas for the Timer PVs (Present values) and the Timer Completion Flags. We will be looking at the timer instructions in the CP1H along with some programming examples. Continue Reading!
Timers and counters are used in the majority of PLC programs. We will not look at how timers and counters can be programmed in the Horner XL4 OCS all-in-one controller. Continue Reading!
Drum instructions are great tools when you have a simple sequence of events that need to occur at a set time interval or as a result of an event. They mimic an electromechanically drum sequencer. The Click PLC has a drum in the instruction set. We will discuss the drum instruction and look at an example of controlling traffic lights. Keep on Reading!
We will look at a PLC programming example of delaying the start of 7 motors. Each motor will be on a switch that the operator can select at any time. The motor outputs should have a 5 second delay between the outputs coming on.
This question originally came from PLCTalk.net. An original solution to the problem came from Peter Steinhoff. His solution is what we will be presenting. It is simple and straight forward.
Continuing our series, we will now look at timers and counters and how they are used in the Click PLC. Previously we have discussed:
System Hardware – Video
Installing the Software – Video
Establish Communication – Video
Numbering System and Addressing – Video
The programming software and manuals can be downloaded from the Automation Direct website free of charge. Keep on Reading!