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OK. I'd suggest simplifying and go back to directly connecting to the serial port of the analyzer and get that working first before moving on to connecting remotely through the serial to Ethernet converter. Do you know what exception response you are getting? In the traffic view of ModScan, it...

You're looking at the Traffic view in ModScan. The black boxes are used to differentiate between requests and responses. The bytes in the black box are the response packets. It appears that your Modbus/TCP Server device is only responding to some of ModScan's requests. And the responses that...

Apparently PNU stands for Parameter NUmber according to the communication manual I was able to find (https://www.manualslib.com/manual/1575268/Danfoss-Ecl-Comfort-210.html?page=25#manual). From what I can tell, it seems the PNU's are in decimal and may be 0-based. So to read PNU 38 in ModScan...

Check your wiring. There is no agreed upon standard for the polarity of terminals labeled "A" and "B". You may need to swap your + and - wires. Also make sure you have a 3rd wire for signal reference connected between your USB to RS-485 adapter and the ECL's "S. Gnd" terminal. What error...

The Modbus (RS-485) connection for that drive is the "SP" and "SN" terminals located on the terminal block. You need to wire the drive's "SP", "SN", and "L" terminals to a USB to RS-485 adapter's +, -, and GND (a.k.a. COM or REF) terminals, respectively. I also recommend ensuring that the...

I already explained the Slave ID. Please reread my post #4 above. 0x83 (hexadecimal) is equal to 131 (decimal). I can't say for certain whether not having a battery connected to the PS would affect communication. My guess is that it shouldn't, but only the manufacturer could tell you for sure...

Communication issues are almost always caused by one or more of the following: incorrect wiring, incorrect communication settings, or incorrect communication packets. In order to help you, you need to provide more details. What is the vendor and model of the USB to RJ12 adapter? Is it a USB...

The Function you have selected in Modbus Poll is incorrect. It should 04 Read Input Registers (3x), as you had selected before. Also, I recommend accessing only a single register for now until you get things working, so set Quantity to 1. Regarding the configuration of the Ethernet adapters on...

There are a lot of places where things could be incorrect (wiring, configuration, addresses, etc.). If you're getting a timeout error, and not a connection error or similar, chances are the TCP connection between Modbus Poll and the ZLAN 5143D are succeeding, it's just the Modbus RTU request...

From how I interpret the Slave ID settings described in the DRS-240 manual, the A0 and A1 pins on CN12 are what set the Slave ID. Since there are only two pins, there are only 4 possible Slave ID's that can be set. The possible Slave ID's are 0x80, 0x81, 0x82, and 0x83 (that's 128, 129, 130, and...

As I'm sure you already know, the DRS-240-48 supports only Modbus RTU (the serial version of Modbus). The most straight-forward way of connecting a Modbus RTU device to a PC using Modbus Poll is to use a USB to RS-485 adapter. An internet search returned no results for the ZLAN5142D serial to...

There is not a standardized protocol that all brand/models would use. Typically, each vendor implements their own, proprietary communication protocol (usually simple ASCII-based messages) that they document in their user's manual for the weigh scale. That being said, some scales may implement...

Yes, you will need a DB-9 male breakout board such as this: https://www.gridconnect.com/products/rs232-male-breakout-db9-male-to-terminal-block-adapter The 3 wires you have from your RS-232 device are TX, RX, and GND. Connect the TX wire to pin 3, RX wire to pin 2, and GND wire to pin 5.

1) The short answer is termination resistors may not be used because termination may not be needed on this RS-485 bus. Termination is used to prevent reflections (i.e. the signal reaching the end of the line and "bouncing" back, slightly attenuated and in opposite polarity) on a transmission...

One additional thing to add. You can perform the following test to rule out an issue with your USB to RS-232 adapters or the null modem cable. Connect both USB to RS-232 adapters to your computer (they should enumerate as separate COM ports) and connect them using the null modem cable. Use a...

A USB A port means the device is a USB host, just as a computer or single-board computer would be. So for this application, you will need Qty.2 USB to RS-232 adapters (one connected to the vacuum pump and the other connected to your computer) and a null modem cable. You do not need, nor should...

You probably already suspected this, but there is some byte-shifting at play here. Keep in mind, Modbus deals only with 16-bit registers (encoded in big-endian order "on-the-wire", i.e. in the packet). Combining or splitting registers is outside the scope of the Modbus protocol itself and is...

Unless the datalogger has a dedicated serial (RS-232) port in addition to USB, I don't think you'll be able to connect via a RS-232 serial connection. The USB connection is NOT the same as a COM port. While there are many devices that implement what is called the USB Communications Device Class...

Glad to hear you got it working. Out of curiosity, what virtual serial port software are you using?

I'd suggest simplifying your setup and working up from a basic proof-of-concept. First, run two instances of a terminal emulator program, such as PuTTY. Configure the virtual serial port crossover software you're using to link two COM ports, connect the PuTTY instances to each COM port, and try...