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Yes, with an outboard DIN rail mount module, you can get two 4-20mA otuputs from a Precision Digital. I did exactly that one time for the same reasons - one 4-20mA pressure signal in, two 4-20mA pressure signals out. Precision Digital stuff www.predig.com - PD6060 (dual input panel meter...

Yes, serial ports are still found on many of the four wire field instruments. Almost all the vendors of Coriolis meters have an RS-485 serial option or a model that is Modbus RTU/RS-485 only. Most magmeters have a serial port option for Modbus. Because magnetostrictive is a higher...

Get out your wallet. The Fluke 773 is a clamp-on 4-20mA sensor with a re-transmit 4-20mA output. I can't afford one, so I'm not sure whether the re-transmit output is powered by the Fluke battery or whether it is loop powered. When I win the lottery, my first purchase will be a Fluke 773.

Your registers are contiguous and they are valid registers. The slave/server is unlikely to throw a Modbus exception code because it's just supplying data from registers. Modbus is "data agnostic", it doesn't care what the data are or represent. It's up to the Master/client to interpret the...

> At openings of 30% valve lower that 30%, the flow values is 0. I did not catch that the DP zero reading is only below 30%. Check the low flow cut-off setting in both the DP transmitter and the control system.

Equalizing valve on 3/5 valve manifold is either leaking/bleeding or remains open.

Another thought - lack of bias to voltage supply or ground on the RS-485 driver lines can cause problems. ICP-DAS makes a small module that provides a wiring terminal block for connecting +V, ground and switching the bias to the driver lines. Spec sheet here...

1. It could be as simple as the 'one-offset' issue; the difference between cardinal and ordinal numbering. A Cardinal Number is a number that says how many of something there are, such as one, two, three, four, five. An Ordinal Number is a number that tells the position of something in a...

1. I'd read the thread here http://www.control.com/thread/1403632021 2. I'd re-read the app note "Ten ways to Bulletproof RS-485 Interfaces" www.ti.com/lit/an/snla049b/snla049b.pdf I'd figure it's time belt and suspenders all around: 3. Cabling: foil and braid shielding over...

A ground loop between the control output and actuator input can generate enough current through AI's impedance to ground to offset what the actuator sees as an input (demand/control setpoint) value. If you test the actuator input with a floating voltage source (battery powered), like a...

HART temperature transmitters are HART temperature transmitters. The one thing that might differ is that Rosemount sets its failure mode output low level to 3.9mA, not 3.8mA. From the Rosemount 644 manual: "If the sensor temperature is outside the range limits, the transmitter saturates...

You can spend the same amount or more messing around with other technologies that don't do the job well (like you've already discovered). Or you can go to what you've already identified as the proper technology, load cells, and get the brand that'll give you best 'weigh' around a potential issue...

Here's my anecdotal experience with an installation of Plantscape, a SCADA version of whatever Honeywell's DCS was probably 15 years ago, for what it's worth. The installation procedure was about 40 pages long. The configuration of the model PC-server was considered critical, as was the...

1) If - simulating 4-20 strokes the actuator, and - the 4-20 control signal coming from the control system is working, and - the feedback pot provides a voltage feedback proportional to the actuator position then the actuator should operate OK. 2) Stroke the actuator, in place...

> 3 pot with blue black brown wires. Which color wire connects to V+ on the controller end? Which color wire connects to V common on the controller end? Which color wire connects to the wiper on the controller end?

Presumably the 2nd RTD element is just a spare and there is no available analog input for the 2nd RTD for redundancy purposes? If the 2nd RTD's purpose is just a spare and not redundancy, then I would not wire the spare element to the JB, unless the RTD is inaccessible and for the sake of...

>>instrument air minimum pressure in the plant is increased. Everywhere I've been the air supply regulator is set to a maximum pressure, not a minimum. In fact, as air useage increases, the air pressure at the outlet of the regulator drops or droops, a characteristic of ordinary...

At least one major vendor requires a serial number for the actuator motor in order to supply the correct wiring diagram (there are hundreds of variants, apparently, for a given model). That vendor also does not glue a wiring diagram inside the motor terminal box cover. Are you sure that the...

Hello Taho. Welcome to Control.com Modbus is a master/slave protocol. A Modbus slave is silent, unless spoken to, at which point it responds with a reply message. A Modbus master always initiates communications. Unless the master is actively 'polling' a slave, the serial communications...

What instrument was used for the topside measurement? Vapor actuated thermometer? Liquid-in-glass? bimetallic thermometer? To what depth was it immersed? How long was it immersed? Has the mechanical thermometer ever been cal'd or checked against a standard? Those mechanical...