Protocol Benchmarking - Modbus

The numbers in the tables below represent the ideal throughput for the data pump use case (data traveling from a protocol adapter to the Predix Edge MQTT Broker to the Cloud Gateway to Time Series).

The tests were executed in a controlled environment with one adapter running at a time, under ideal network conditions with a local time series simulator. The rate was deemed successful if there was less than a 1 percent loss rate over the course of a multi-hour test. Based on the testing, data loss rates dramatically increase as tag counts pass these thresholds.

The tested VMs were configured as follows (with a 2GHz vCPU):
Table 1. Tested VM Configurations
VMProcessorsRAM (GB)Disk Space (GB)
VM (small)115
VM (medium)2420
VM (large)4820
Table 2. Modbus-Poll
EnvironmentPeriod (seconds)Acceptable Tag Rate
VM (small)11350
109225
VM (medium)11200
109525
VM (large)11425
1011850
Predix Edge Gateway 30021675
104650

The number of tags per adapter does not scale with the device’s performance characteristics. It is recommended to add new adapters to support higher tag counts along with corresponding physical hardware to support the additional applications.