The advantages at a glance | |
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The FETCH/WRITE API enables accessing of S7 PLC data. This allows direct access to data packets, inputs / outputs, flags, peripheral inputs / outputs, timers and counters. This does not affect the S7 PLC programming. All that is needed is the establishing of an additional communication link.
The following connection types are possible:
You can configure communication via the FETCH/WRITE interface by specifying the size and location of system data areas and access speed.
Data are extracted as individual information objects, and they can also be transferred as individual information objects. Simatic addresses and target system addresses may be freely assigned. This method can also be used to limit the data volume to be transmitted to what is absolutely necessary. An Excel file can be used to configure device data points (see also ipConvLite. Of course, the ipConvLite standard functions also include data point processing, scaling and conversion.
Information can be time-stamped locally in ipConvLite to keep track of changes. This means the internal clock of ipConvLite must be synchronized first. You can do this using the installed protocol (e.g. IEC 60870-5-101) , NTP or an external GPS/DCF77 module.
The state of communications with Simatic determines information object quality attributes,i.e. if IEC 60870-5-101 is used as the target protocol, , and the connection to Simatic is disrupted, all the information objects transmitted take the value “invalid” or “not topical”. Upon reconnection, all data points take the value "valid" and are transmitted to the control system with their currently valid values.
For further details see ipConvLite.
This example shows a gateway upstreaming data to a remote control unit via the IEC 60870-5-101 protocol. Process data is also provided for local monitoring and control via the OPC Classic DA XML interface. | |
This example shows a redundant configuration. The redundant coupling can be realized over a serial RS232 line or over Ethernet. |