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RS-485 is just a transport mechanism for binary bits. Any number of protocols, sets of rules for communication and how data is packed can run over RS-485. I seriously doubt that the communications protocol is Modbus, therefore, using a Modbus master utility won't do anything. A Google...

5167 uses differential pressure for flow calulation. So the use of an absolute pressure transmitter says that a flow computer is being used to convert from volumetric flow to mass flow with temperature and static pressure compensation. Mass flow static pressure uses absolute units.

I opened the catalog of a T/C vendor and found a limit of error table for extension wire. https://s15.postimg.org/6gpczedln/Limits_of_error_for_extension_wire.jpg It appears that the standard limit of error for K wire is the same value as standard limit of error for thermocouple wire, but...

You don't say how "does not work" manifests itself - Master times out? Exception code? Whole network comes down when you add #7? What exactly happens when you add #7? Error log messages? But, if #7 works OK stand-alone then you know how to wire it and poll it. Did you leave the...

> I can poll both HP and HVAC and get values. If you get VALID values from each device, then the physical RS-485 network connection is functioning. 1) Why the "response not from expected slave" error? If you're getting valid data from each, then it isn't clear how the slave ID's could...

Get a standalone Honeywell UDC2500 PID controller with its SP Rate setting with separate Engineering units rate UP and Engineering units rate DOWN settings. https://i.postimg.cc/SRNp7K8C/01-SP-Rate-and-EU-per-hour.jpg Talk to it via Modbus for SP and PV.

You are correct mag meters need to be in the pipe. Clamp-on transit time ultrasonic technology is used to read potable water flow (without particulate or bubbles; those are the domain of doppler technology). I doubt you will find 'cheap' sensors. Ultrasonic technology requires exciting...

Yes, RS-485 is technically 3 wire, the 3rd wire a signal common. It usually works OK on the bench with 1m cabling and no common mode between nodes, but 485 is not isolated like Ethernet is - NIC Ethernet cards used do transformer isolation with that little black 'magnetic' cube. RS-485 hub...

From the 344 manual: "If diagnostics detect an input sensor failure or a failure in the transmitter electronics, the transmitter drives its output to low or high depending on the position of the failure mode switch. If the sensor temperature is outside the range limits, the transmitter...

Page 751 (Section 5.7) in Liptak's Instrument Engineers' Handbook, volume 1, 4th Edition, is a one page comparison of Electronics Pressure Sensors, the sensing elements.

I'm lost. What's a pulse width modulated 4-20mA signal look like? A square wave at 4mA or 20mA? With pulse widths based on what kind of time frame?

That sounds like a mis-designed RS-485 network with 120ft stubs to a central point in a star topology. Google RS-485 hub and you'll find hardware solutions for RS-485 with long stub runs like this. Presumably whatever protocol you're going to use has some device addressing and can run on 485.

This 10 year old thread addresses ultrasonic differential measurements http://control.com/thread/1026222097 I've used what was Milltronics, is now Siemens, with two transducers connected to a single controller, the HydroRanger 200. The controller interface was updated a couple years ago...

Yes, but if you want reassurance B&B Electronics publishes the distance vs the baud rate chart for RS-485 communications, assuming 24AWG twisted pair cable (CAT 5 cable) and a balanced interface (RS-485). https://s17.postimg.org/cx0cgy0z3/cable_length_vs_data_rate_for_24_AWG_twisted_pair.jpg...

Google RS-232 current loop A current loop modem converts from RS-232 voltage to a current loop for the long haul and then back to RS-232 voltage at the other end.

If by 'digital' you mean a communication protocol like Profibus or Foundation Fieldbus, buy a replacement DP pressure transmitter that covers the same DP pressure range and is made of the same materials. Replace the pneumatic DP cell with the Fieldbus model and connect to your digital Fieldbus...

When the total resistance in the loop exceeds what the power supply voltage can drive current through, then the transmitter's output drives current up to the point the voltage supports, then faults in some mode. I saw this in action the transmitter repeatedly attempted to re-intialize (go...

You're right. As long as you have thermocouple or T/C compensating/extension wire on both sides of the connector, the error will be limited to whatever thermal gradient there is between the connections. Go for it.

One reason to use liquid fill is that liquid fill lubricates the movement's moving parts which reduces the effects of wear and extends the lifespan of the gauge. Is extended gauge life worth the price of quality liquid fill fluid?

See what Rosemount has to say about materials compatibility http://s22.postimg.org/q1kz43vlt/03_H2_S_compatability_Rosemount_Pressure.jpg