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12" at 500 bar? Not your stock magmeter. This sounds like an application for a clamp-on flowmeter (that doesn't care about the pressure because it doesn't 'see' the pipe pressure), but I have no idea whether GE/Siemens/Flexim models are suitable for subsea service.

I hope this is a school assignment because flow metering a valuable petroleum product without a flow meter is a silly idea. Level is good for making volume based decisions like, "is there sufficient product to make the next batch" or is there "sufficient empty volume to accept a load of...

None of the documents on the web for this device mention Modbus. Why do you think it has Modbus registers?

1) You are doomed to failure if you experiment with the serial settings (baud rate, parity). Don't experiment. Configure the settings to match on both ends. Settings must be identical. Modscan configures the serial settings for the PC under Connection (connection > connect > Connection...

This presentation has a FF/serial Modbus box, not generic serial. http://www.fieldbus.org/images/stories/international/asiapacific/India/presentations/bangalore_july12_5_linking_devices_dearborn.pdf

It depends on how you use the word 'calibrate'. Does 'calibrate' mean factory custom calibrated (not the standard factory calibration over the full working range) with the factory's pressure source and calibration gear or does it mean configured to a certain range within its working range...

Q generally designates "flow rate". NL is normal Liters, Nl/hr means "normal liters per hour". It is a volumetric flow rate for air (or gas), but calculated to 'normal' conditions, where Normal conditions are a given temperature and pressure whose values I don't recall off the top of my...

I, too, am not quite sure why you would split loop control PID between an HC900 and a PLC, unless it is a purely academic exercise in Modbus. The HC-900 is technically a Process Automation Controller, a PAC; it is not a DCS. If you are using the Honeywell brand "Control Station" as the HMI...

1. Does the original software" use the same RS-232 or RS-485 port as you're using for Modbus? On a lot of devices, the mode that the port operates in has to be dedicated to either 'configuration' or 'communications' and it won't switch back and forth between those modes. The serial port...

One of the bullet points in the Manufacturing Automation link is "Rugged". The anecdote that always stuck with me was Morley's recollection of the on-site demonstration of their PLC. While lugging the heavy carrying case up a stairwell to get to wherever the test location was, the case...

If you use that Acromag 894 four channel math module, then you could probably use two channels for your control analog outputs and use the 3rd channel as an analog/fake discrete channel to switch between the control outputs. That module uses a sort free-form math so something like: A =...

I assume you need to switch between the two analog output signals, not combine them in some fashion. Way back in the early 80's I had to do something like that using a couple DPDT relay (I seem to remember sourcing gold plated contacts which are supposed be best for low current 4-20mA...

It's my impression the FO-to-ethernet conversion is quite commonplace. If you use a Modbus RTU (serial)-to-Modbus/TCP converter at the RTU end, then it's Ethernet packets all the way from there to the DCS. I'd recommend a converter that specifically handle Modbus, as opposed to a generic...

Hardware-wise, 4 wire RS-485 is capable of operating full duplex, but by jumpering a half duplex port is created. The slave drive does not need full duplex functionality (the ability to send and receive at the same time). The sequence of Modbus event is sequential (one following...

I suspect that others are as confused about your question as I am because there's no answer after a couple days. What do you mean by the 'range' of a PID Controller? Its input is its input (considered 0-100% by the controller), its calculated output is 0-100% unless configured to some...

No experience with your stuff, but no converter is needed. In fact 2-to-4 wire converters are not even available commercially, because all the other 4 wire RS-485 Modbus devices run as 2 wire devices when the same polarity send/receive driver lines are jumpered just as you state: SDA and RDA...

Roy, the use a toroidal probe - that's a clever idea. Thanks for bringing it up.

A DP level transmitter always has a 'wet' connection at the low elevation tank connection. A wet leg is used for the high elevation connection when the vapors at the top of the tank tend to condense to liquid in the impulse line. When the condensate/liquid collects in a dry leg, it applies...

Whose simulator are you using? What configuration have you given it? (like value 123.456 in register 400031)

Put the controller in manual mode, then - go to 0% output and check the valve response - go to 50% output and check the valve response - go to 100% output and check the valve response I suspect that you will get a fast response and that the valve/positioner response will mimic what you...