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Welcome to the forum, John. I'm near the end of a career in process instrumentation and SCADA data collection and contribute to the fora because I can remember how difficult it was to discover some of the things I learned the hard way in the course of troubleshooting problems. I hope you...

Modscan is a great tool for checking, confirming and troubleshooting a Modbus connection and the data format, but it might not be the right tool for displaying data on a continuous, operational basis. A SCADA or HMI software package with a Modbus driver might be more what you need because those...

Thanks for the very interesting historical note - the bipolar ±12VDC power supply for a 4-wire pressure transmitter. That precedes my experience. I just assumed two wire, loop power for an industrial pressure transmitter because that's been my experience and it just goes to show - assumptions...

A past US President, Bill Clinton, frequently made the statement, "I feel your pain". I'll echo that sentiment as an appropriate statement for your frustration at the circumstances when there's so little feedback from so many posters. As a long time veteran of web fora, I came to grips...

FYI, by convention, Hexadecimal is used when documenting the fields in Modbus messages. I don't think I've seen anyone provide decimal numbers before. Hexadecimal works well because Modbus Holding and Input data registers are 16 bit registers, so each data register is a 4 digit hexadecimal...

Are you sure of your engineering units? a rather substantial 50 PSID drop across a flow element? An increase in flow of 150% (900gpm/600gpm = 1.5 = 150%) will produce a corresponding increase in DP of 225%, an increase from 50PSID to 112.5 PSID. sq rt of 225% DP (sq rt of 2.25 normalized) =...

Contact Saftronics and ask them how to repair or replace the drive's keypad/display. https://www.saftronics.co.uk/contact-us/

Electronic differential pressure transmitters are commodity items nowadays (really old pneumatic output DP's are not, they are obsolete) - there's a dozen major league players that produce excellent, reliable products. Their origins were for flow measurements across orifice plates in the...

>I’m assuming that the master must poll every single slave all the time to read some discrete input state but since I don’t see any real life proof of concept it must be because modbus protocole isn’t suited for that? I have a hard time figuring out if the polling of every slave can cause...

The output has to be used by the controller's physical output - the 4-20mA output or time proportional on/off modulation within the cycle time period. So output is 0-100%.

>So PID formula will only apply during (100 - (40/2)) to (100 + (40/2)) . i.e 80C to 120C. If measured temperature is current below 80C, then output is 100% on & if above 120C then output is off completey? Is this it means? I did not read all the subsequent posts some of which seem to...

Please use a statement like "Modscan can read register xxxxxx" instead of "I can read register 4000" because "I can read" it does not inform the community as which application (Modscan or Kepware) reads register 4000. The photo you posted shows Modscan reading (3)4xxx: Input registers. floating...

>Will change in sheath OD causes any change in accuracy of T/C? No, no change in accuracy.

I can't recall where I got these, but E is Exposed, G is grounded and U is Ungrounded

1. Presumably you have a manifold valve between each pitot tube and its DP transmitter. Swap/exchange one of the three good-working transmitters with the bad boy transmitter. If the problem moves to a former working-good location, then there's an issue with the transmitter. If the problem...

Your corporate limit of 6m of capillary length is somewhat less what is available for commercial remote seal assemblies from major vendors (depending on diaphagm size). Commercial capillary length limits are likely due to - a xmtr-capillary-diaphragm combination accuracy limits at reference...

I'd say you're lucky if you've only encountered one FP format over a number of years working with Modbus. For integer info, I'll refer you to Wikipedia's page on integers because I'm not a programmer, just a Modbus implementer. https://en.wikipedia.org/wiki/Integer_%28computer_science%29...

Executive summary: Endianess can be and is different for data formats than it is for the bit order in serial transmission Section 4.2 in the "MODBUS Application Protocol Specification V1.1b" is source of your quote "Modbus uses a big-Endian representation for addresses and data items." Here's...

This is known as a Zombie thread, rising from the dead. The original question was asked in 2004 and answered in 2005 and now you re-open it in 2020, a testament to the power of search engines. You might luck out and someone reading this will have 15 year old software and some experience, and...

1. Is this a correct summary? At the present time the measuement system is: A. Probe #1 is Type T Thermocouple with a temp transmitter sending a 4-20mA signal scaled 0-160 Deg C to a DCS. B. Probe #2 is Type T Thermocouple with a temp transmitter sending a 4-20mA signal scaled 0-160 Deg C to...