Thumb Wheel Switches on Input Modules

[immunoman 0]

Is it possible to connect more than 1 thumb wheel combination on a single input module? Logix 500 requires thumb wheel data entered to the word level so the only way to enter 2 combinations must be to delimit one from the other. If this is possible, how would it be done? My same question refers to Logix 5000 as well only its case delimiting the tags.

[b_carlton 61]

What do you mean when you use the word 'combination'? How many input points? 4? 8? I'm presuming you are inputting decimal numbers, given your previous posts. If you have a 16 bit input module you could have 4 - 4 point wheels. The individual 4 bit sections can be moved to individual words by logic if that's what you need. Or are you talking about more input points that you have on one input module? Then it gets a little more complicated.

[immunoman 0]

I'm inputting (3) 3 decimal 4 point digit entries. How many input modules would be required and with how many points? How would the addresses be assigned in Logix 500 and 5000?

[b_carlton 61]

That isn't very clear. Are you saying you have three entries, each entry consisting of 3 digits?

[Sergei Troizky 26]

Looks like you need to connect 3 thumbwheel switches with 4 outputs each, but trying to avoid connecting more than one per input word because of some instruction limitation. You can connect them to any inputs and move them in the software to different words for further processing, e.g using move with mask.

[BobLfoot 301]

For one Input Card of 16 bits you can connect 4 thumbwheel switches. It is done as follows: Assume 16 point input card is I:1.0 on an SLC 500 Switch A wires to I:1/0 ; I:1/1 ; I:1/2 and I:1/3 Switch B wires to I:1/4 ; I:1/5 ; I:1/6 and I:1/7 Switch C wires to I:1/8 ; I:1/9 ; I:1/10 and I:1/11 Switch D wires to I:1/12 ; I:1/13 ; I:1/14 and I:1/15 Now a MVM can load I:1/0 thru I:1/3 into N7:0 for the value of switch A Now a MVM can load I:1/4 thru I:1/7 into N7:1 and a Bit Shift then Moves N7:1 into N7:2 for the value of switch B Now a MVM can load I:1/8 thru I:1/11 into N7:3 and a Bit Shift then Moves N7:3 into N7:4 for the value of switch C Now a MVM can load I:1/12 thru I:1/15 into N7:5 and a Bit Shift then Moves N7:5 into N7:6 for the value of switch D A different approach is if you use Diode Isolation and DC Input and Output Cards you can tie multiple thumbwheels to the same input point and energize the switch you want to read with the output. A single output card of 16 points and a single input card will support 64 thumbwheels in this configuration.

[TimWilborne 108]

I'm sure there is a good reason, but have you thought about using an inexpensive two line display to replace your thumbwheels? You could probably do it for less than the input cards, much less the thumbwheels and wiring

[JesperMP 2]

My thoughts as well. Thumbwheels in 2009 !? Hmmm. how about using a 4 digit 7-segment display, and a thumbwheel to display parameters one by one ? And with two buttons for plus and minus you can even change the parameters. I think I can find some code from 1985 or thereabouts. Tip: These thumbwheels better be very well maintained and regularly checked, or you will get some funny machine behaviour.

[TConnolly 13]

Optimate has some dirt cheap (about 200 bucks) interface units that allow you to set values for a limited number of registers. Nematron has apparently purchased the optimate line. http://www.nematron.com/products/industrial/optimate.html I've used several of these units. An OM613 or OM413 might be what you need. You should also check out Redlion's Kadet. http://www.redlion.net/Products/HumanMachi...face/G304K.html If you want to use thumbwheels then how you do it depends on whether you want three different single digit numbers or one three digit number. Either way wire all three thumbwheels to the same input module. If you want a single three digit number then its super simple: Treat the input word as a BCD and use the FRD instruction to convert it to a binary. If you want three separate single digit numbers then it gets a little bit more involved, but not much. Bob gave you the basic method. However, if you use the masked move MVM instruction then you need to be sure and clear the destination value first because MVM masks destination bits, not source bits. Using the AND instruction saves you having to first clear the destination word. To shift the bits four positions to the right divide by 16. To shift bits eight positions to the right divide by 256. Here is how I would do it with thumbwheels: First Digit AND I:1.0 000FH N7:0 Second Digit CPT N7:1 (I:1.0 AND 00F0H)|16 Third Digit CPT N7:2 (I:1.0 AND 0F00H)|256 Considering the time involved to wire thumbwheels you'll probably come out ahead with one of the small data entry type HMIs. Edited 16 Jun 2009 by Alaric

[Sergei Troizky 26]

Thumbwheel switches versus even the smallest and cheapest HMI display: - Anyways are less expensive. - Are much smaller. - Are more robust mechanically and withstand higher temperatures. - Do not require specific power supply and do not consume power. - No need in programming software, cable, PC, learning the software. - Do not occupy (often the only) communication port, and do not require this comunication cable as well.   Yes, they occupy inputs, but in some systems an extra port may cost more. - Are simpler for understanding by regular operators (3 of 4 are idiots from my decades-long experience).

[BobLfoot 301]

Just curious Sergei but what industry is your primary focus. I could be wrong but I suspect the thumbwheel / hmi debate is dependent on end use target audience.

[JesperMP 2]

Only if we are talking about very few thumbwheels (2-3 ?), will they be less expensive let alone "smaller". How do you display alarms ? A lamp for each alarm ? Tying up a port on the PLC ? While we are at it, grow up and ditch that PLC if it does not have ethernet. It has happened, serial is over, ethernet is here even for the smallest PLC. Making non-basic machine these days without a panel is an anacronism. I'll bet that making a machine without a panel means that you accept some limitations only because of that.

[Sergei Troizky 26]

My understanding of the initial question was exactly a basic machine with 3 thumbwheel switches and nothing was said about alarms, lamps, etc. And the question betrayed a novice, so let him learn simple things before getting involved with networking.

[BobLfoot 301]

Thanks for the response and participation. The above clarifys things for me a lot.

[JesperMP 2]

If he can connect his PC for programming, then he can also connect an HMI. If he can program a PLC, then he can also program an HMI.

[TimWilborne 108]

Alright I was just wanting to make a suggestion of an alternate product to the thumbwheels... I think the argument has been made, both for and against the thumbwheels, so why don't we let this rest until Immunoman comes back and clarifies

[pandersen 0]

I would also suggest the Bit Field Distribute instruction rather than masked moves or bit shifts for turning the inputs into numbers (as long as you have RSLogix 5000, of course. I am not sure it exists in 500) BTD(Local:1:I.Data,0,ThumbWheel1Value,0,4) BTD(Local:1:I.Data,4,ThumbWheel2Value,0,4) BTD(Local:1:I.Data,8,ThumbWheel3Value,0,4) BTD(Local:1:I.Data,12,ThumbWheel4Value,0,4)

[OkiePC 14]

Even easier than MVM, BTD, CPT, and also faster execution and platform independent: Just map the bits with 12 rungs input0 N7:0/0 ] [-------( )--- input1 N7:0/1 ] [-------( )--- input2 N7:0/2 ] [-------( )--- input3 N7:0/3 ] [-------( )--- input4 N7:1/0 ] [-------( )--- input5 N7:1/1 ] [-------( )--- input6 N7:1/2 ] [-------( )--- input7 N7:1/3 ] [-------( )--- input8 N7:2/0 ] [-------( )--- input9 N7:2/1 ] [-------( )--- input10 N7:2/2 ] [-------( )--- input11 N7:2/3 ] [-------( )--- Edited 18 Jun 2009 by OkiePC