Ethernet to Serial (RS485)

[TheWaterboy]

I'm using a Lantronix xPressDR+ for serial to ethernet to serial encapsulation to an RS485 ASCII string of instruments. The software part (ComPortRedirector) give the PC a normal COM3 interface for Kepware to connect to. That traffic gets sent over the network to the device that then converts it to RS485 and bobsyouruncle.

This thing works but the config and serial monitoring software is just junk. Documentation is as well. There isn't much to configure but knowing where it really is and what's important is guesswork. Even their latest "Device Installer" software shows settings from the device that disagree with what the devices own web interface says.

Anyone have one of these they like for the process instrumentation? Not a laptop dongle - something meant to be used on the factory floor in our industry with good diagnostics, live serial port monitor and clear configuration.

 

[the_msp]

I use a lot of Moxa, although most of mine are for RTU to TCP (MB3170). Have a look if they have a model that suits your needs. Reliable and easy to config. Good documentation.

 

[JordanCClark]

RTA has one that does ASCII to OPC-UA. Been wanting to play with one, but don't have anything around to connect it to.

https://www.rtautomation.com/protoc...t/?pa_protocol-selector-2=ascii,opc-ua-client

 

[TheWaterboy]

This application requires a poll/response script to follow that I would have a tough time replicating in logic. I'm using the UCON plugin in Kepware to run this.

I still haven't had the chance to do anything using OPCUA so I don't yet understand it well but I don't think that would make the difference here. It's not a protocol conversion as much as the scripted automation that limits my options. a dumb serial port is the ideal.

.. Well the IDEAL solution is a standalone module I can put the scripted demand/response automation into at a reasonable cost but that continues to elude me.

 

[shawn_75]

I use the XPress DR (without the +) and find that using wireshark to inspect the packets sent to/from it to be the easiest way to troubleshoot the comms. A lot of the settings are in hex. What settings are you having issues with?

 

[Ken Roach]

I would reach for a Red Lion product for this kind of application. I'd probably aim for the middle: the DA10/DA30 with Crimson 3.1, not the classic DataStation Plus or the cutting-edge FlexEdge.

They have well-isolated serial ports, a scripting language similar enough to ANSI C to do most simple poll/response work, a webserver to easily whip up some diagnostic HMI sort of stuff, serial or Ethernet debug consoles, and on the newest units onboard PCAP capture.

I'm not sure if a DA10 or DA30 can run as a conventional COM port redirector sort of serial terminal server.

I did a simple reverse-engineered poll/response application with the classic DataStation Plus about three years ago. I swore out loud when I realized the original protocol authors had just taken a Modbus RTU driver and swapped the order of the CRC bytes, then called it their own.

 

[TheWaterboy]

The issue I am having is that the machine that uses the virtualized com port has a problem with an unrelated application and while I sort that out I need to reboot a lot. I have found that after a reboot the com port is there but "closed". I have to go into the CPR app, and open the port which seems to kick it off and then all is working again.

But the "opening" of the port in the software is supposed to be just for testing using its internal diagnostic routines. I shouldn't have to kick start this every time it reboots.

I'd also really like a window that shows what serial commands it's passing.

In my original plan for this device I envisioned 2 hosts using this as the same com port to the same destination (a redundant pair of data collectors ) , but it seems that it wont do that either, once it gets locked onto one host it doesn't listen to the other one anymore.

I've seen that Red Lion series of devices mentioned a lot - I didn't want a lot of complexity just for a com port but if it could possibly do the command response (+math) polling it might be worth looking into.