Best PC to PLC communications for Sorting

Hello all,

I am currently reseaching the best way to create a simple sorting system. My challange is that all sorting decisions are made by the PC by doing a DB lookup from a scanned barcode.

I would like to send the result from the PC application (Custome vb.net) to a bit shift register in the PLC so I can track the package to the lane.

I not sure the best way to have the PC update the PLC register. Currenly I am leaning towards a Siemens PLC but other PLC's are not out of the question.

Does anyone have a suggestion of how to get this communication to work? I can program the PC and program the PLC just not sure how to get them to work together.

Any suggestions will be appreciated.

Thanks,

Andy

I have not seen this done with Siemens, but I have something similar with CLX and a PC. We used the developer’s version (OEM) of RSLinx, with a simple "C" routine to transfer the data over Ethernet. In our case, we moved several words of information on a regular timed basis. To insure the data was being exchanged, we used a watchdog timer. The biggest issue here was network traffic and bandwidth. Care had to be taken to make sure the network was not overloaded by fast refresh rates.

It has also seen this done using serial communications, and VB. Again this was Allen Bradley, PLC5 in this case. This was accomplished using the built in Serial ports on the PLC and PC and a null modem cable. RSLinx was not needed in this case. In this case, the distance between the PLC and PC can be an issue. There are work arounds, but the closer the better. Seed was plenty good for our process, and the exchange was very reliable.



Both systems ran well for years. I'm sure that Siemens offers something similar or maybe even better.

We're using SICK barcode systems and Siemens S7 400 PLC's. The barcode is read and sent over Profibus (have seen serial comms as well). SICK have also developed their own Siemens interface blocks for use within Siemens, to manipulate the data and messages correctly.