1.2.2.2            Number of SCADA nodes required

This is probably the first thing to decide. How many SCADA nodes do you need?

The number of SCADA nodes you needs depends on:

·  The Physical Location of your Automation Devices. Are they all close enough that they can connect to a single SCADA node?  If yes, then one SCADA node might be the answer.  

If the automation devices are far apart and cannot be connected to a single SCADA node, then you need a SCADA node for each location.

·         The automation network used.

o        Does it support Multiple Masters?  If not Multi Master, can the automation network be split into multiple smaller networks? If the answer is no to both, then one SCADA node is required.

·   Reliability. Multiple SCADA nodes provide a distributed architecture that is more reliable. WebAccess also provides Redundant SCADA nodes that will automatically switch to the backup and redirect Clients to the backup SCADA Node. A Hot Standby might be an inexpensive solution.