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See post #2

It's not a problem, it's a standard feature on 4-20mA transmitters: fault mode. The control system needs to know that there is critical process error, an empty pipe, which is apparently coded F051 by this flow meter. The transmitter drives the analog output into fault mode, which in this case...

ANSI/ISA publishes a standard for instrumentation symbols, but the 'key' or 'legend'on the local P&ID sheet is the most important because there's a lot of customization. The instrumentation standard is titled, AMERICAN NATIONAL STANDARD ANSI/ISA-5.1-2009 Instrumentation Symbols and...

I remember several instances where inexpensive single loop controllers running Modbus RTU could be choked by bombarding them with 10-20 Modbus read commands per second. In one case the master ran Modbus/TCP through a gateway and polled the poor slave at 20Hz, never waiting for reply. Slowing...

It all makes sense, but what constitutes a "Null" write command that the slave would not acknowledge or return an exception code for? Does an null write mean the data field in the write command is number zero: 0000? I'm drawing a blank on a "null write command".

Give it try and see. Input conversion number is a multiplier factor.

Good Luck on your 20 year old Rosemount magmeter that offered upgrade to a D model 19 years ago: The 8172 manual states the gain factors apply only to the 8712U, so that tends to narrow the probabilities of making an adjustment on the magmeter electronics: Most PLC's and DCS's have a...

Ground loops can cause a higher than expected current in a 4-20mA circuit. But what is the likelihood of a ground loop developing in a working system? The fault is more likely a component failure on either the transmitter side or the PLC AI receiver side. Disconnect the leads. Short the...

Try searching NEMA vs IEC contactors

Hopefully an alarm someone pays attention to. "If hydrogen gas remains in any area in a concentration from 4% to 75% (the lower and upper flammability limits) in air, then the atmosphere in that area is flammable". Page 3, Hazards when Purging Hydrogen Gas-Cooled Electric Generators...

There are thousands of devices that have Modbus serial communications and if Modbus is available (sometimes only as a paid option) then Modbus is mentioned. Devices that do not mention Modbus do not have Modbus implemented. It would possible to implement Modbus but not release details of how...

I have had problems with consumer grade switches needing period power resets which I put up with a short while and then I replace. Of course, one never discovers the root cause for a problem with a disposable consumer product. Please tell us what you find. I'm really curious.

Every thing has been working for years except for the new guys, all the same model. Hmmm. Any chance this box runs on some version of Windows CE? Sure sounds to me like a 'memory leak' problem and what leaks better than windows?

I have never seen values cited for constructing a HART filter but you can peruse the tidbits I've collected in looking for such. Rosemount DVC6200 manual has some information using a HART filter, their own HF340...

You need a loop isolator. There are different flavors of isolators, depending on whether the output side is active or passive, whether the isolator itself is loop powered or DC powered. The Transmitter side has to be capable of handling 48Vdc of loop power. THe Mark-Vie side has to be...

Every transmitter has a maximum range that it can measure. You don't something for nothing so you don't get 1.25 bar out of 0-1.0 bar transmitter. The so-called smart transmitters allow you to range or scale the output to some range smaller than the maximum range of the transmitter, but do...

Wrong baud rate will cause a Time-out. Presumably you have the ECL software? You should probably check and confirm the baud rate at PNU 38. from the manual: 6.2 RS-485 Baud rate The baud rate for the RS-485 bus can be changed by writing 9 (for baud rate 9600), 19 (for baud rate 19200) or 38...

1. ECL 310 Modbus Manual here: https://assets.danfoss.com/documents/latest/206108/AQ074886472234en-010602.pdf 2. Any reason you're running Modbus RTU over 485 instead of using Modbus/TCP over Ethernet? 3. biasing The 310 has internal termination and polarization/biasing. Their...

Your PC is connecting to only one ECL 310, correct? Otherwise you'd likely have a conflicting default Slave node ID addresses.