Applies To:
  • CitectSCADA x.x

Question: What is the maximum practical number of nodes supported on a network? 

The largest project I know of has 60 nodes on a single network talking to the same Citect servers. This system is using Windows for Workgroups 3.11, Citect version 2.11 on Pentium 100 and 486/100 class computers over non switched 10Mb Ethernet. With the 60 nodes the performance of the system is around 2-3 seconds. This performance limitation is not due to the number of nodes on the network but the PLC protocol performance. I would expect such a system to be able to handle up to 100 nodes. Since this system was installed we have made various performance improvements in Citect. There has also been much faster Pentium Pro computers released as well as much faster switched 100Mb network hardware become available. I would also expect that using Windows NT with such hardware should allow a much larger maximum. This could be up to and possibly greater than 255 nodes. The exact limit will depend on exactly what the Citect project is doing, how much data each client is requesting and other background load on the Citect servers.