Chris Elston Posted October 6, 2004 Report Posted October 6, 2004 ERAN FISCHER (eranfischer@hotmail.com) on Wednesday, October 6, 2004 at 12:25:17 --------------------------------------------------------------------------- question: Usage comments: I have a project to connect a PLC to our self cleaning water filter. Do you know of any good site that can help me decide on which PLC to get, or can you make any recommendations. all I need is for the PLC to measure differential pressure between the inlet and outlet of the filter and send a signal to a 3-way solenoid. in the future we will also add a motor to this filter that will work only for 10 seconds when the solenoid is being energized. Thank you Eran Quote
Guest Posted October 6, 2004 Report Posted October 6, 2004 (edited) Greetings Eran, first of all, welcome to the forum ... next ... what type of instrumentation do you have on your filter system? ... specifically, what devices are you using to measure the inlet and the outlet pressures? ... do these devices put out 4 to 20 mA signals? ... or 0 to 10 VDC signals? ... or something else? ... as for the 3-way solenoid valve ... what voltage does it need? ... 120 VAC? ... or 24 VDC? ... or something else? ... and how much current will the solenoid coil draw? ... next ... PLCs that will handle the analog input (pressure) signals that you’re talking about aren’t the cheapest things around ... plus, you’re (usually) going to need some type of software to program this thing ... and probably a communications cable for programming purposes ... all of this might turn out to be quite expensive ... have you talked to your filter supplier? ... this CAN’T be the first time someone’s come up with the idea of automating a filter system ... personally I’d shop around a little bit before I started tackling something like a PLC ... but if you’re still interested, just answer the questions above to get started ... we’ll do our best to help you out ... actually, it sounds like a fun little project as long as the expense doesn’t scare you off ... best regards, Ron Edited October 6, 2004 by Ron Beaufort Quote
KinK Posted October 6, 2004 Report Posted October 6, 2004 Hi Eran I am with Ron on this one, why would you look at using a PLC. if the project is as simple as it sounds purchase a differential pressure switch that you are able to change the setpoint on. then take the output from this to turn on a timer or solinoid or pump or what have you. if you are determined to have some sort of controller that you can reprogram then I suggest that you look at something like the omron zen unit it has analog inputs and is very cost effective and sounds like a really good fit. omron zen Quote
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