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>based on the FTDI chipset. I second the nomination of the FTDI chipset. Just today I installed a USB/RS-232 converter with an FTDI chipset on a Windows 7 box and it worked immediately, just like the others I've installed in the past 6 or 7 years. In contrast, last week a colleague got...

Whoops, took a closer look. Correction to the diagram. Wiring should be 24Vdc (+) to Sensor (+) Sensor (-) to PLC (+) PLC (-) to 24Vdc (-)

You don't say which positioner you have. Some positioners have keypads and a menu. But if you have to use HART, this blurb http://issuu.com/rmcprocesscontrols/docs/dvc6200-fdt-brochure says Fisher's Fieldvue "digital valve controllers (positioners) with HART communications can be...

You should look up the part number on the relays that switch the RTD signal and make sure that the relays have gold plated contacts. The excitation current for an RTD is generally < 1mA, and such low currents require gold plated contacts. Any resistance added in an RTD circuit appears as a false...

Assuming that the symbols at the 24Vdc power supply are (+) and (-), what you drew is a classic circuit for 2 wire, loop powered instruments. So yes, if it's a 2 wire loop powered device, that'll work.

It isn't clear to me exactly what the problem, "all over the map" means (no examples provided). If the temperature drifts on the backup indicators but not on the controller and you believe the controller, then the indicators are not stable. If the indicator shows an offset from the...

OPC was originally promoted as an alternative to DDE, a Microsoft protocol for communicating with and populating an Excel spreadsheet. There are software packages that do talk to Excel through an OPC server. Depending on what your end goal is, you might investigate data acquisition software...

Sounds like a conventional pressure regulator to me, with the inherent proportional droop in flow rate as flow rate increases.

The idea is to - have two condensate pots, one for each impulse leg, at exactly the same elevation - have a constant level of water in each leg, so that at all flows, the head pressure of the liquid column in the impulse tubes will be equal, and therefore will contribute any pressure to either...

Electromechanical pressure switches need no power to operate, the line pressure on the sensor element activates the snap action electrical switch(es). Large elastomer diaphragms or bellows for lower pressures, metallic diaphragms or pistons for higher pressures. United Electric, SOR, Ashcroft...

Practical Distributed Control Systems (DCS) for Engineers and Technicians IDC Technologies. - 569 pages https://idc-online.com/content/distributed-control-systems-dcs-17 (take out any spaces the forum inserts into the URL) IDC Technologies offers courses, this might a text for their...

correction - gallon of water weighs 8.34 pounds

What about re-locating the bubble tube? $10 of plastic pipe . . . Did you correct for specific gravity? A 3-5 foot error on 20 foot tank is 15%-25%. Specific gravity could easily account for some of that error, if no such compensation has been applied. (To find the SG, go grab a gallon...

>1) How to Transfer the Data from Slave Device to other Slave device using Modbus TCP? A modbus master queries/polls a modbus slave with a message requesting data. The slave responsds with its data, or an error message. >2) does it use special software? The modbus master is...

potential free contacts Contacts can be potential free in a standalone device, but for any means of control some voltage/current has to be present in order to sense the presence or absence of the voltage/current. So some voltage has to be applied to your 'sensor' contacts. 24Vdc is...

The analog signal, 4-20mA, is used worldwide because - it is simple and rugged - in its 2 wire, loop powered form it gets its power over the same wires as the signal - in its 2 wire form, it can be designed for Intrinsically Safe approval for use in hazardous areas, which allows...

Thanks for the excellent review. I'm going to get one just to try it out.

The loop powered isolators I'm familiar with scavenge power from the loop power supply (on the input side) to drive their own electronics and the loop current on the output side. If it were me, and I had a loop powered isolator lying around, I'd try it. force the source to max at 20mA and see...

Either there's a delta P and flow path so the meter is indicating true flow or there's true zero flow and the meter is falsely indicating flow. Since I've seen numerous examples of true flow when the pump is off with low flow sensitive clamp-on transit time ultrasonic flow meters, I tend to...

Ans: No. The solution Mr. Myres recommends is exactly what the alarm input board spec calls for - dry contacts. The alarm board design allows for a universal solution with practically no knowledge of electronics: dry contacts. Relay contacts are dry contacts as long as you don't connect any...