Control.com - Nerds in Control

Hello,
i want to talk to some meters useing Modbus RTU across ethernet.
I have a RS 485 serial to ethernet converter, is that possible with the Device? Or do I need a special Modbus Ethernet converter.
I have the ADAM 4570 from www.advantege.com, but I am wondering, why they sell a special Modbus Ethernet converter .... my Modbus network is a 2- Wire RS485....

Thanks in advance, Carsten

Use your RS 485 serial to ethernet converter.

the single biggest factor in determining compatibility with converters is timing. since ethernet is packet-based, in can impose delays into the serial stream. modbus-rtu doesn't tolerate delays >13ms. this should be fine for most adapters on the market, provided that network routing is kept to a minimum. this involves the physical and virtual architecture (e.g. if you're trying to maintain control across a company wide network, or (worse) the Internet, you'll have troubles, especially if you have a busy network - do you like to download streaming video on the same network?).

also, if you're network admin permits it, converters in UTP/IP mode are faster, have less overhead and provide the kind of timing you likely need, but many network admins don't permit it because it floods the network with traffic.

if you have a managed network, your admin can probably set it up to permit UTP/IP across whatever segments you'll be using, without letting it flood the rest of the network.
The downside of UTP/IP vs TCP/IP is that it is more likely to introduce errors into the data stream over very large packet switched networks, but is generally just fine in smaller networks.

Cheers
Bradley, bscook@dewcomm.com

Hey Bradley,

thank you very much. But, one more question, do you know, how I can determine the Delays? Is it enough, if I PING the RS485/Ethernet Gateway, and make sure that the time is smaller than 13ms?

Best regards
Carsten

Try using a terminal server