First, a little history. Ethernet was developed by Xerox between 1973 and 1974. The developers were inspired by ALOHAnet and named ethernet for the “luminiferous ether”. a long disproven theory which postulated that light (and electromagnetic radiation) propagated through an invisible cloud of an unknown ether.
There are many devices in use today in the E&P segment that only support legacy communications such as rs-232 and rs-485.
Today the world of automation is getting a little fuzzy with IT departments getting involved in a greater capacity. Remote data connections to field devices are becoming more common, with the devices being moved onto company networks, through VPN tunnels, WAN, & VLAN connections. IT shows up, sets up a Cisco switch at your site and skedaddles, and yet you have these legacy devices that have traditionally been polled with modems or radios. Now what?
One solution I have seen, is to utilize an RTU that may be on site to poll all the data from the various devices via modbus,(if modbus is an option) and store that data until the RTU is polled through its ethernet connection. That requires building modbus tables (and possibly history tables) in the RTU, and working with your SCADA department to retrieve that data.
My preferred solution is to use a serial server or terminal server. Here’s why.
1) Some data may not be required to be integrated into the SCADA system. For instance, I have worked with some Caterpillar compressors and the facilities engineering department wanted to keep tabs on the engines by utilizing Caterpillar’s software. My solution; I was able to install a virtual comport on their laptops, which let them view that data remotely with no protocol storing or manipulating required.
2) Sometimes its easier to give your SCADA department the modbus address and registers and let them build around that. Why do it twice?
3) By using serial servers, it’s quite easy to expand to support more devices.
There are many manufacturers of serial servers available. Personally, I prefer the equipment manufactured by Lantronix. Many of their products also support wi-fi.
P.S., If you also happen to deal with Caterpillar engines, and need to retrieve data, ->HERE’S<- a great way to save your company a few dollars.