7.5.2. Bridging Remote Servers
A special bridging application that the DataHub program makes possible is to bridge remote servers. This is effectively bridging combined with tunnelling.
You can use this to create a software bridge between remote pieces of hardware. For example, consider this situation:
Suppose you need to control a motor remotely. An on/off switch and status indicator light are connected to PLC "A" in one location. The motor itself and a rotational sensor are connected to PLC "B" in another location. Both PLCs have OPC servers connected to DataHub instances.
To make the connection, you would need to program the PLCs for these data points:
| Point | Function |
|---|---|
A.switch
| - Changes value to 1 when switch is on,
0 when switch is off. |
A.indicator
| - Turns on light when value is 1,
switches off light when value is 0. |
B.motor
| - Starts motor when value is 1, switches
off motor when value is 0. |
B.sensor
| - Changes value to 1 when shaft is
turning is on, 0 when shaft is not
turning. |
then bridge them in the DataHub instances like this:
As when bridging local servers, bridging remote servers can also bridge different fieldbus protocols.