As they are so helpful, do they have any example scripts?
As a slight aside, there is a Telegraf plugin for ModBus telegraf/plugins/inputs/modbus/README.md at release-1.18 · influxdata/telegraf · GitHub. Since @Bill.Thomson pointed me this way, I have had quite good success with using Telegraf. It will then output the data received via MQTT so easily then passed to emoncms with no need for InfluxDB.