DDE or OPC server for weighing scale


Thread Starter


We have 4 Mettler Toledo Viper SW weighing scale with only RS232C ports. We want to interface the scale to a single PC and send the data into Wonderware INSQL residing on the same PC. I understand that we cannot multidrop RS232C and need to have RS422 or RS485. Is there a PC card with RS422 or RS485?. I suppose we still have to convert the RS232C signals from the weigh scales into RS422/485 using a converter. We also need either a DDE or OPC I/O server on the PC talking to the 4 Mettler scales.

Any ideas to go about getting the above job done is appreciated. Also my budget is very tight.



I had a similar solution for four Mettler Toledo scales (puma) to interface with Wonderware Intouch 8.0 via the Mettler serial ports of each scale, and added four USB to serial adapters to the PC. I could not find a software package, so I went to http://www.rentacoder.com and posted a bid for someone to write one for me. I had about 40 offers, and chose one for a resonable price. I am having one writen for me to act as a DDE I/O server.

Donald Pittendrigh

Hi All

We have successfully done this using Rice Lake scale integrators fitted with a Lantronix RS232/Ethernet converter and Kepwares OPC server software on the PC. It was tested with InTouch and worked perfectly using OPCLink.

Donald Pittendrigh