PLC-5 Data Concentrator - What is it?

Just came across a configuration that I am not familiar with. In this configurartion, there are several PLC 5/40E rack with local analog I/O cards connected via a DH+ network. Some of the racks are referenced as regular plc's, while the others are labeled as data concentrators. All of the racks have CPU modules in them.

Can someone kindly explain.....

1) The difference between the two?

2) Purpose/benifts for configuring a rack as a data concentrator?

3)Is there a difference in data (block) Transfer between analog modules?

ie. PLC CPU/Analog I/O in local rack data transfer vs Analog I/O in data concentrator rack to it's local CPU?

Thanks

I googled "PLC5 data concentrator" and found a few interesting references.

It seems it is a normal PLC but it's utilization is specialized.

Maybe something more like distributed control and communications? The predecessor to the contrologix gateway? I did not follow the links, but they should hopefully help...

Paul

There's nothing unusual or special about those controllers; the term "data concentrator" is just the label someone has given them.

Often I see a controller called a "data concentrator" when it is gathering data from its serial port
via DF1 Half Duplex or using Modbus modules, then is accessed by a LAN connection over DH+ or Ethernet.

In our case, we have a Data Concentrator which gathers data from 5 networks. Then our Scada system polls the data concentrator rather than the expansive network of PLC's.

The term data concentrator can mean anything - nothing special. My interpretation (as probably most others) is that it is a centralized repository of remote data.

Oakley said:

In our case, we have a Data Concentrator which gathers data from 5 networks. Then our Scada system polls the data concentrator rather than the expansive network of PLC's.

The term data concentrator can mean anything - nothing special. My interpretation (as probably most others) is that it is a centralized repository of remote data.

Click to expand...

Thats exactly what i would describe it as too, it just polls the other PLC's on the network for data then SCADA only has to look at one device

Thank you ALL!