How to use the Tachometer Function of a Counter Timer Tach (CTT)
view a live tutorial demo of how to setup and use this CTT in your automation project.
To setup the Counter Timer Tach for Tachometer mode, just hold down the MODE button for 3 seconds and wait for it to flip over to the configuration mode. We are currently sitting at the Function Menu which you can see right here. You can select one of four functions. We’re currently in timer mode, so let’s move that down to Counter, Tach. Note that we can also select a mixed mode if we want to. Let’s go back to the Tach mode and lock that in by pressing the MODE key. Once we do that the indicator tells us we are now in Tach mode and the outputs got turned on. Press the MODE key to move to the next parameter. You can select one of four output modes. We want the 2Hi1Lo mode which is this one right here … so lets go ahead and switch that – press the arrows to cycle through the parameters until we get to 2hi1lo – press the MODE key to lock it in – and then press the MODE key again to move it to the next parameter. This is how fast the Tach is going to sample the input to make decisions. You can have a 10K cycle per second rate, all the way down to a 1 cycle per second rate. We’ll use a 1K rate for this example, so we’ll move that down to 1K and lock it in by pressing the MODE key. Press the MODE key again and now we get to move down to the POINT menu - this is the decimal point location – that is how many significant digits after the decimal you want to show. Be careful with this one – if you change the decimal point location it will move the decimal location on your set points but WON’T move the numbers. So suppose for example you had 15 seconds as your set value but then you move the decimal point over – well the 15 will stay where it was, the decimal point will move so now you have a set point of 0.015 instead of 15. So set this BEFORE setting your set points! Let’s move on to the next parameter by pressing the MODE key. This is our scaling parameter. This modifies the present value display so you can convert the displayed value into whatever units you want – for example you could multiply by 1/60 or .01667 to convert the display from pulses per second to pulses per minute. Let’s move down to the next parameter – which is the Delay Time. This tells the Tach not to start until after the amount of time you specify here – anywhere from .1 to 99.9 seconds. We’ll leave that at zero for this example. Press the MODE button to move down to the averaging parameter. This is great for making the present value more stable. You can average 1, 2, 4, or 8 samples Press the MODE key to move down to the next parameter – this is the minimum width of the reset pulse – you can choose between 1 and 20 msec – choose the wider pulse if you are concerned about noise getting onto the lines or de-bouncing switch glitches. And finally, press the MODE key one more time – and you can select what kind of input are you connected to PNP or NPN – it’s important to set this right, otherwise you may get unexpected results! Once ou are done, hold down the MODE key for three seconds, wait for it to flip back into operation mode and you are ready to go. Set your set point there – let’s say we want a set point of 10, lock that in … then you can set your second set point by pressing the MODE key, now we are looking at set point 2. Adjust that value – we’ll make him something bigger than 10 – how about 20 … lock that in and the Tachometer is ready to go. That’s all there is to setting up the Tachometer. Be sure to check out the other videos in this series to get the most out of your Counter Timer Tach module. And as always, please send us any topics you would like to see covered – or - any other comments for that matter – we appreciate the feedback!