Flight Simulator PLC Control

[ROCHESTER]

Hello,

I'm a Mech-E. I do HVAC, but flight sims are my hobby. I'm building a F-16 cockpit(pit) and am looking to use a SLC 500 type PLC to do the I/O <-> between the PC and pit's dials, switches, analog instruments, and motion system. I'd like to buy the stuff used(cheap) on eBay.

The flight sim software runs on a Windows PC and uses a &quot;shared memory&quot; or &quot;mem_mapped_file&quot; to exchange date. A small background app. reads and writes data to/from the main program.

The I/O list is roughly as follows:

Digital inputs - 350
Digital outputs - 250
High resolution analog inputs (>=12-bit) - 8
Low resolution analog inputs (>=8-bit) - 16
High resolution analog outputs (>=12-bit) - 16
Low resolution analog outputs (>=8-bit) - 16
Rotary encoder inputs - 8

I need a system latency for the analog I/O no greater than 20 msec. The digital could be 10x slower.

Here are my questions:

[ol][li]Am I in the right ballpark for a family of PLC?
[li]Is there anything I'm overlooking in the above?
[li] Can I use the older SLC 5/0x systems that use the serial RS-232/484 protocols? Or do I need to go with the much more expensive Ethernet systems?
[li] Could you point me to good literature that explains comm protocols between PCs and PLCs?[/li][/ol]

Any help here would be greatly appreciated.

Craig

 

[djs]

Hello;
Several things: As far as I know most if not all of the SLC analog cards are either 14 or 16 bit resolution. Second point is that you will not get 20 ms cycle time from these cards.
A much better solution would be to place I/O cards within the PC. National Instruments offers a full line of discrete and ananlog I/O cards.

 

[killemall]

SLC system would be very expensive, and not all that fantastic. It looks like a reasonabley large system. Too large to place IO in the computer.

I would be inclined to go for a control logix over the SLC, as the mathematical abilities are way more advanced. It also has advanced interupt abilities.

Weather you need to go ethernet or RS232 is dependant on how much info and how fast you need to transfer it between the PLC and the computer.

Go to the Allen Bradly website, and look at the IO selection guide for specs.

I am no more help than that.

 

[ROCHESTER]

djs,

I'm interested in SLC 5/0x because there are lots on eBay for much less than new price. NI stuff is very expensive, even on eBay. And, I'm familiar w/ AB SLC's.

killemail,

I'll look into the control logix systems and read up on the specs.

Thanks y'all

 

[PLucas]

Bricklayer,

Without knocking this forum or the people who contribute here, I feel that you might receive more help and suggestions if you posted this question on a dedicated PLC's only forum. Try here:-

http://www.plctalk.net/qanda/

There are a few regulars there who would love to contribute to a project like this.

Give it a try, you have nothing to loose.

Paul

P.S I have no affilliation with the forum I have mentioned in this post, I am just a user.

There are 10 types of people in this world.....
Those that understand binary and those that don't!

 

[ROCHESTER]

PLucas,

Thanks for the link. I'll check out the forum.

 

[AGomaa]

Another option you may think of is selecting a PLC CPU that does not run any program. With the I/O associated with it acts as external I/O to your PC application. So you will gain high speed and may be lower cost.
A typical product is the Automationdirect H4-EBC , F3-OMUX-1, etc. (an RTU to your PC)
I do not know if such modules will support your I/O requirements but they have a bundle of similar products that may be suitable.
Other manufacturers have similar products as well.
Good luck

 

[jraef]

I have used this company's products instead of PLCs when the PC is going to do most of the thinking. I recommend the Adam-5000 ethernet system. It is a similar rack and I/O card system, but high speed (relative to PLC-PC communications) and inexpensive. Example, 16 channel digital output card for $85US, 8 channel high speed analog input card for $283US! I doubt you will find SLC500 cards that cheap even on ebay.

http://www.advantech.com/estore/products/sub_category.asp?Category_ID=1@29958&bu=iag

&quot;Venditori de oleum-vipera non vigere excordis populi&quot;

 

[ROCHESTER]

Hi jraef,

Thanks for the link. the Adam-5000 looks pretty interesting.

I think you'd be supprised what you can get on eBay.

http://search.ebay.com/search/searc...ht=1&SortProperty=MetaEndSort&query=1746-NI4+

I'm looking at using a slave PC linked to the PC running the flight sim software with an Ethernet network. I want to use sound cards for cheap analog I/O.

I'm thinking the slave computer would be almost free. I must have 5 old Mobo's laying around with a few ISA sound cards. If the processor speed doesn't need to be too great... This would be determined by both the overhead from the multiple sound cards as well as the network stuff.

I looked it up and the game port has the following:

* 4 8-bit analog(axis) inputs
* 4 digital inputs

So, you get 4 8-bit resolution analog inputs with each sound card. For the high resolution analog output I hope to do the following:

1. Write a small app that generates a sinewave signal on each of the stereo channels.
2. Read the sim's &quot;shared file's&quot; floating point value(e.g. altitude)
3. Scale the floating point value to a frequency value
4. Set the frequency of one stereo channel to the frequency value
5. Make a frequency-to-voltage(F/V) circuit for each of the stereo channels
6. Use the voltage analog output to drive pit device(e.g. altimeter I/P transducer)
Movie of altimeter -->

http://mysite.verizon.net/vze323mw/sitebuildercontent/sitebuilderfiles/Video 6.avi

For the analog inputs you do the reverse.

1. Generate a proportional voltage signal from the pit device(e.g. head-tracker x-axis angle)
2. Convert voltage with a voltage-to-frequency(V/F) circuit
3. Connect the V/F circuit to the mic or line-in of the sound card
4. Read the frequency of the input in software
5. Scale value to a floating point value
6. Either send the value to Falcon4(e.g. head position) or use for pit control system(e.g. FF for pedals)

I've been playing with MSVC++ and kludging together some code to try to do this. I've gotten independent sin wave signals going to the two stereo channels. Now I've got to try it with 2 sound cards and rig up a F/V circuit.