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On the clamp-ons that I've used, a positive reading is forward flow and a negative reading is reverse flow. The connection of the sensor cables to the correct terminals determined the polarity of flow value, meaning that reversing the cable connections reversed the flow polarity. There's...

1. measured TEMPERATURE by Thermometer is OUTPUT of field device(SALVE), but this signal is INPUT for PLC(MASTER). Correct. A temperature transmitter's input is an RTD or thermocouple sensor. A temperature transmitter's output is a scaled 4-20mA signal proportional to temperature. A PLC's...

I stand corrected. The initial draft and versions of the User Manual had to 20/21 register addresses, but only just now did I realize that the latest version 2800 User manual that I linked to above has the standard register addresses for integers, but the user manual still lacks the floating...

Isn't this a Purchase Order/checkbook situation?

If you're going to roll your own HMI, then there are some things to be aware of: 1. You need to download the UDC 2800 vendor manuals: For the UDC 2800: User manual R200.0 rev 8 51-52-25-157 Sept 2023, not an earlier version. The Modbus maps are for Function Codes 20/21 which are rarely, if...

Reading/Changing SP, PV and OUT This is nitty gritty stuff but it's critical to understanding what all you need to make this work. Modbus is a just protocol which is a set of rules for communication. The rules cover things like who talks, who listens, how a connection is established, what...

As found: FC01 & FC03 : is to read OUTPUTs of SLAVE. (Memory area named Coil & Holding Register respectively). for example : A binary sensor when it is ON or OFF. These ON or OFF will be READ by FC01. An analogue value such as temperature or pressure value will be READ by MASTER by FC03. Should...

Yes, I can help you from the UDC2800 side, but I don't know one end of a snake (Python) from the other, so you'd be on your own for Python coding. But I need to make sure that the magic of Modbus will actually move you toward your goal, because I have encountered numerous situations where...

There's an inexpensive book that covers the basics of Profibus, Catching the Process Fieldbus: An Introduction to Profibus for Process Automation. by James Powell. Profibus installations should use Profibus cabling and connectors because their designed for the hardware layer operation...

That's a nice graphical representation of Modbus data transfer. I might steal it. A couple points: One minor point, for whatever reason, one usually sees the leading zero used with the low order Function Codes: FC01, FC03, FC04. Maybe because when they're listed numerically they appear 'in...

In Modbus, inputs and outputs are relative to the slave device, being the slave's input or the slave's output. Inputs can be discrete or analog. Outputs likewise, can be discrete or analog. The reason to use Modbus to write a value to an output is to force that output to a given value...

A spec sheet/manual is on-line here: https://edata.omron.com.au/eData/TCs/H038-E1-03.pdf Page 6 shows an output module being inserted into a socket, so apparently this model had interchangeable control output modules. I did not find a listing for output module p/n's in skim read, but those...

I would summarize that the statement in post #3 by saying that, the variables can be custom mapped in Modbus registers. But there are no specifics. Probably because the specifics of custom mapping are associated with the software development tool used for that purpose which appears to be...

> Between the start address and the reference address, I can place my data. I've never used this unit, but that assessment doesn't appear correct. Take the No 6 internal register on your attached table. It is assoicated with a physical slot no, designated as a Holding Register, where 03...

So you've confirmed that the transmitters do not support Modbus RTU in their current configuration. If you installed Modbus RTU on the transmitters, then yes, the open source app would communicate with the transmitters. But. There's a big But. Whether that open source app will be of any...

The protocol on the first couple pages is a proprietary ASCII protocol; it is NOT the Modbus ASCII protocol. page 6-5 in section 6.2.3 states that Modbus RTU is documented in Section X (10). Note that on many devices, Modbus in any form might well be an option that has be purchased, it might...

Since this Zombie thread has come back from the dead, I'll take the opportunity to post the link to a free instrumentation and controls book available in standard pdf format. The book includes the fundamentals of math, chemistry, physics and electronics, but the bulk is about instrumentation...

One would hope that the factory would provide information, but Honeywell had no one who could or would answer actuator questions. If it wasn't printed in the spec sheet or manual, you were on your own. Back 15 years ago, Beck could not provide a wiring diagram without the serial number from...

Good luck answering your question. I'm told IEC 60034 covers motor duty cycles, but I don't have a copy. When I dealt with 90/160° actuators (typically on valves, occasionally on a damper) I could not find a factory guy to explain which "S" class category their smaller torque (HVAC) motors...

One, FSC, is a safety controller; the other, Experion PKS, is a process control system. This page says that Honeywell's FSC was a first generation Fail Safe (Safety) SIL3 Controller, it is now obsolete and has been replaced by Safety Manager...