This section evaluates the performance of BACnet services over ARCNET networks.
Message length of request and reply frames is 25 bytes and 30 bytes, respectively, including frame overhead of the ARCNET protocol.
The performance improvement for ARCNET is much more significant than it was for MS/TP networks (compare Figures 9 and 10 with Figures 5 and 6).
A comparison of Figures 11 and 12 shows a significant difference in performance between ConfirmedCOVNotification and UnconfirmedCOVNotification in ARCNET networks.
In real applications, traffic generation patterns in Ethernet can be different from that in MS/TP or ARCNET.
Comparison with the results in Figure 9 shows that ARCNET networks saturate at a lower value of G than Ethernet networks when the number of nodes increases.
Comparison with the results from ARCNET in Figure 10 shows that the average service delay for Ethernet networks is smaller at light traffic loads, but that Ethernet is saturated at a lower value of G.
Similar to the MS/TP and ARCNET networks, all the nodes in the medium transmit COV notification messages to a central controller node when a COV occurs.
Comparison with the results from ARCNET in Figure 12 shows, once again, that the network resource for ConfirmedCOVNotification service in Ethernet is saturated at higher values of G when the number of nodes increases.
This study examined the delay characteristics of three popular BACnet LANs: MS/TP, ARCNET, and Ethernet.