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I recently used the Softing MobiLink handheld communicator with a paid license to talk to Foundation Fieldbus transmitters (needed a separate FF power supply). That same MobiLink is capable of Profibus PA communication with a Profibus license.

Here's a link to a spec sheet for a frequency-to-4-20mA signal conditioner: https://api-usa.com/pdf/api/api7010g.pdf There are other brands and models

Analog output Siemens ships its magmeter converter/transmitters with the 4-20mA output disabled, one has to enable the output to get a signal. What does ABB do? Is the Watermaster output loop powered output? If so, is the loop being powered with a DC power supply? If the 2nd loop powered...

I have no experience with these products, but are you sure that the serial communications is a 7 bit word and not an 8 bit word?

RS-485 is daisy chained and does not like stubs. The stub cabling from the connection to field device from the network bus 'T' point 'junction' point should be short. You can't just parallel a number of stubs out from a 485 pair of driver lines. Yes, a pairs of terminal blocks work - Pair 1...

The protocol you referred to as Modbus RS-485 could be either Modbus RTU or Modbus ASCII. Modbus RTU is much more common than ASCII. That's one of the things you have to establish, is which protocol is in use? Both ends, master and slave, need to talk the same protocol. An RTU device will...

The most important lesson you can learn in your project is using the available documentation and working to understand what that documentation is telling you. Getting the exact documentation for the device you're using should be at the top of your "To do" list. You'll find forum questions like...

To be clear, the RS-485 converter is a pass through device, it is neither slave nor master. The Raspberry Pi device is the Modbus master in this case.

You might try connecting Simply Modbus to the 2nd RS-485 and see what the effect is. No telling how sophisticated the unit is, but it just might map Modbus to a separate memory for both RS-485 ports. Who knows?

1. >I'm also a bit unsure how to read the data (e.g. 1013). Is it a holding register, input register or ? The leading numeral in parentheses indicates whether the register is a holding register or an input register. Leading numeral (4) is a Holding register, like (4)1013 or (4)01013 Leading...

Jschulze beat me to it while I was reading your reply. Yes, parameter H37 configures the "unit address", which may be the Modbus slave address. Presumably the parameters are entered via the keypad HMI on the heat pump. Yes, you can check the Modbus ability with the Modbus master slave tools...

1. Please confirm that there is only one and only one RS-485 port on this heat pump. 2. Please confirm that the Wi-Fi access point is connected to a USB/485 dongle which is connected to the one and only one RS-485 port. 3. Please confirm that the heat pump is communicating via WiFi to...

1. If you're getting bits back and forth, it is probaby not a hardware issue involving a terminating resistor. It could be, at higher baud rates and longer distances, but probably not. 2. Is it a Modbus protocol? My first reaction is, is the protocol Modbus RTU, based on your statement, "I...

Jumpering the 4 wire to 2 wire should work. The drive manual told him that it can be done and how to do it. It's done all the time. I've done it numerous times.

My domestic water heater experience convinces me that the hardness minerals precipitate out (we have really hard water). I find brownish chunks of precipitated minerals, about size of cereal granola, collecting in the bottom of my domestic hot water heater when I have to change-out the lower...

The flow must be so low that it is like a differential relay (constant flow regulator) for a bubbler, like you mentioned early on, 'the bubbler'. Interesting that the flow is low enough that the chemist didn't pick up the 5 grains of hardness in the condensate. As you say, if it works, leave...

Curious_One, Is the cooling water just dripping onto the surface of the condensate pot for its evaporative cooling effect or is the the cooling water is being added to the condensate pot through the fill port on the condensate pot?

What a beautiful example of the KISS (Keep it Simple, Stupid) principle, "We simply routed a 1/4 inch copper line to the upper pot though an adjustable needle valve. The slow trickle of cool water stopped your well documented effect" and still working 30 years later. I love it!