Figure 5-76. Network Throughput Analysis At 1200 Baud - ABB TPU2000 Technical Manual

Figure 5-77. Network Throughput Analysis at 19200 Baud
Analysis of the simple example yields a few points to be considered when analyzing system throughput. Each
element involved in communication timing contributes significantly to overall throughput. If the host executed and
updated faster, overall throughput could be improved. If intermediate devices were inserted within the network,
transaction time would increase proportionately. Baud rate is only one of many contributing factors in calculating
system throughput. If one network access was required for retrieval of system data, overall network efficiency
would be improved. If in a networked system, the protocol utilized would allow for additional data request
commands while the slave device is processing a response, Network throughput time would be improved.
Virtual treatises have been written on improving system throughput and data updates. This simple example
illustrates and allows the user to calculate system throughput times. This is especially critical so that the system
user will not be surprised with overall system response.
ABB has implemented features within the protective relay to maintain system data integrity. Latched bit status,
momentary change detect are a few features implemented within the various implementations of the Modbus
protocol.
TPU2000/2000R Modbus/Modbus Plus Automation Guide
Percent Contribution at 1200 Baud
Host Latency
48%

Figure 5-76. Network Throughput Analysis at 1200 Baud

Percent Contribution at 19200 Baud
RCV Latency
3%
Host Latency
93%
RCV Latency
24%
MSOC Latency
1%
TX Baud
Latency
27%
MSOC
Latency TX Baud
1% Latency
3%
RCV Latency
MSOC Latency
TX Baud Latency
Host Latency
RCV Latency
MSOC Latency
TX Baud Latency
Host Latency
253