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jstalman

Micrologix 1400 HSC

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Hello, I am pretty new to the PLC world and currently have a project involving a 360 PPR encoder. But I am not getting very many pulses. I had 13 revs of the encoder and only received 37 pulses. I have also attached a 4.7k pull down resistor thinking that might help. I went to setup a HSC on my 1400 but it wouldn't let me select it. All I have is HSL and RAC the rest of the options are grayed out.. What would be the best way to set this up? Ive attached my logix in case someone needs to view it to get a better idea of what im doing. Thanks Much Jesse rewrap.RSS

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You are trying to use the high speed inputs totally incorrectly. Get the manual for the 1400 and read the section entitled "Using the High-Speed Counter and Programmable Limit Switch". The High Speed Counter Function File is the center of your control. You may have to shift some of your inputs around. I suggest using Mode 0 which will use I:0/0 as the input. Edited by b_carlton

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I downloaded the 480 pg manual before posting but didn't see that section I also looked again. Is it buried in another section, am I look at the wrong manual or am I just blind? Is this the same manual that you have? When I wrote the ladder I didn't intend on using a high speed counter but when it wouldn't count all the pulses I figured I would have to now. But thanks for the pointers.

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found it I was looking at the user manual not the instruction set reference. Thanks for your help!

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Also you were resetting your 'encoder counter' (C5:0) at the same time as C5:1. And it had a preset of zero. Were you going to count as many pulses which represented one inch, increment C5:1 (using C5:0's DN bitZ) then reset C5:0 to count up for another inch?

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What I wanted to do was see how many pulses equaled 1 inch before I put a hard value in the preset, also i wanted to reset the encoder counter every inch and the inch counter after the setpoint was met. I don't know why I reset them both at the same time. Is there a better way? Again this is my first program that I have written from the ground up any insight would be great. I am a maintenance technician but I'm tiring to get more into the programming side of things.

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I was just a little confused by the setup but since you were just starting then ok. I'm sure with using the HSC you'll be fine. We use it all the time with encoder input and it counts ok. Though when we do a new project I keep forgetting the filter time and it starts up showing very few pulses (captured as it's coming up to speed). I then set it and it takes off. I see you already have that, though too low a setting will count noise.

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Thanks one more question I have read the section on the high speed counter and I think its setup correctly, now to use it in the ladder do I use it as a bit with a CTU like I currently have or do I move the HSC:0.0 to an integer file and use a compare function in the ladder? Im a bit confused. Sorry to be bothersome.

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Correct, you don't use a 'counter' instruction (like CTU) at all. You refer to the accumulated count as you mention (except it's HSC:0.ACC). You can set up an interrupt program file, put its program file number into HSC:0.PFN, enable an interrupt by placing a '1' into HSC:0.UIE then in that program file test for HSC:0.MD (Mode Done). This means that the high speed counter jsut passed the High Preset (HIP) and has wrapped to the Low Preset. Use that to increment your inch count. (add one to a count, don't try to use a counter). Edited by b_carlton

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b_carlton, If you have a free minute can you look and see what Im doing wrong here? Maybe show me how you would do this. Thanks hsc test.RSS

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I'll have to wait until Monday. I only have the free version at home.

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