| You can use the S7-OPC server from
Siemens. It is available free of charge on the Siemens Simatic Net
May 2000 CD. This OPC server comes with a SEND-RECEIVE interface,
which is what can be used to connect to the CP535 card. The
SEND-RECEIVE interface will not allow reads and writes to the same
job, so two jobs were set up in the OPC server and the CP535 card;
one for SEND and one for RECEIVE. This also meant that if I wanted
to read and write to the same address in the PLC, I had to define
two tags, one referencing the SEND job, and a second referencing
the RECEIVE job. In the Citect OPC client, you will need to
configure 2 devices (one for the read only (RECEIVE) tags and the
other for the write only (SEND) tags). |
