Looking for ideas to log equipment down time

Here is the problem. A client company has about 100 pieces of equipment that they want to track when and how long they are down for service. The equipment can be a few hundred feet from the nearest computer. The requirement is for one computer to track every piece of equipment. The interface will simply be the user equipment operator hitting a button when the equipment goes down and then hitting another button when it goes back in service or a toggle switch. Most likely a red and green button with a corresponding red and green indicator LED. The software I will write will log changes in the status of the equipment into a database.

My first thought is to use a USB digital IO board and use network cabling to connect the switches to the IO board.

Any other ideas?

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Chris W
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Chris W
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If they are networked you could track the mac addresses.

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Best Regards:
                     Baron.
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Baron

Just to clarify, the pieces of equipment in question are NOT computers and there are NO computers near the equipment. A signal must be sent a few hundred feet to another room on another floor in the building to the nearest computer to do the logging. Also the equipment is not all in the same place.

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Chris W
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Chris W

I bet somebody has a really clever solution for this, but until then I'll offer a thought. An important goal would seem to be to keep the wiring effort to a minimum. If you're going to have LEDs you're going to have some power at the switches. What about an 8-bit parallel-to- serial shift register at each switch. Encode the bottom 7 bits with a switch ID using some form of jumpering, and use the top bit to hold the switch state. Wire all the boxes in series and then to read the switches you supply a single LOAD pulse followed by 800 clock pulses to read in 100 switch-ID-and-status bytes.

If you guarantee that the tail end of the wiring string always feeds

1s to the last SR (wire up each SR input with a weak pullup), you can just send out bursts of 8 clock pulses until you read back a value with all 1s, indicating that all the connected boxes have been polled. In this case you just don't use the switch ID value of 0x7F as a valid ID. Then also, if you have a break in the data line, you will get an all-1s byte before you have read all your switches and you will be able to detect that. You'll also need to analyse what your return signal will look like with breaks in the V+ line, GND line, LOAD line and CLK line, but in any case it will be easy to distinguish any of those from valid data.

Mike

Reply to
Mike Silva

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First thing that comes to mind is something using the 1-wire network devices from Maxim (formerly Dallas Semiconductor).

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The devices have an internal hard coded unique serial number and often some ram so you can store attributes of equipment. You can communicate with them over a pair of wires on a shared network. Using the I- buttons you could have a tech or operator touch a touch-point to take it out of service, then another to take it back into service. I bet you could get creative with it.

Reply to
Mike H

You're going to need at least two wires to each box, preferably 3: common, "down", and "up". In an industrial setting I might even recommend four wires (two twisted pairs, much like telephone wire); then for a protocol use 4-20 mA current loops. You'd need as many receivers as there are equipments, or maybe two, since you need two signals from each equipment.

These receivers "should"* be a 4-20 mA interface for each channel - I can't imagine these not being available commercially. The advantages of the 4-20 mA loop are incredible noise immunity, and there's a built-in fault (e.g., broken wire) detector: if there's (are?) 0 mA in the loop, it's broken. (that is, 4 mA means "start" and 20 mA means "end" or however you want to arrange it.)

You might want to try a google search on "4-20 mA receivers" or thereabouts.

Good Luck! Rich

  • should: the way I would do it. ;-)
Reply to
Rich Grise

If there is Ethernet in all those rooms you can use LAN-LabJacks. But they are about $400 a pop.

Simpler solution: Post a phone number, an "equipment down" code and an "equipment operational" code number on each machine. Use a telephone interface at the PC and let that be the only thing answering this number. The rest is, ahem, ducking for cover here, just software.

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Regards, Joerg

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Joerg

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Yeah.

Why not make the equipment itself be smart enough to send error codes
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Reply to
John Fields

--snip--

Chris,

If (and I realize it's a big IF that assumes facts not in evidence ) all of the equipment is electrically powered, and if (another big one) all are powered from a common power source, would it be sufficient to monitor when each piece of equipment was drawing power and when it wasn't?

I know that inductive current-detecting modules exist (think clamp-on Ammeters); the hairy part would be locating the electrical power lines and attaching the modules.

I admit I'm a little unclear on your statement about placement:

Does this mean that computers already exist, but none are close to any given piece of equipment? That is, that a 100m RF link _could_ be set up between each piece of equipment and at least one computer, and that those computers are networked?

Along the same lines, should we be picturing 100 pieces of equipment, all within 50' of each other, but a hundred-yeard-dash away from the nearest computer? Or 100 pieces of equipment scattered across 20 acres (or at different locations across the country) which are (say) in the middle of National Forests, well away from any computer?

Frank McKenney

-- "If men were angels, no government would be necessary. If angels were to govern men, neither external nor internal controls on government would be necessary. In framing a government which is to be administered by men over men, the great difficulty lies in this: you must first enable the government to control the governed; and in the next place oblige it to control itself. A dependence on the people is, no doubt, the primary control on the government; but experience has taught mankind the necessity of auxiliary precautions." -- James Madison / The Federalist Papers

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Reply to
Frnak McKenney

How about getting a few cheap Palm PDAs, and let the maintenance folk take one to the machine, open the datebook and add a notation '#7734 OFFLINE' with the current date/time. At day's end, return the PDA to its dock, and let 'em all sync (Bluetooth or otherwise) to the master datebook.

Overkill, but mass produced PDAs are cheaper than running wires and installing buttons.

Reply to
whit3rd

Thanks for all the suggestions. I think I like the phone system idea the best.

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Chris W
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Chris W

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