ModMaster Manual v3.10 - 3.4. Polling
If you want to read or write all the defined registers, you can use the Poll Once button on the Register Table page. This causes ModMaster to make a pass through all the register definitions, writing to the slave those registers that have the write flag set, and reading the other registers. The pass is done in model address order (i.e. in the order that the registers are displayed in the register table).
If you click the Poll button on the toolbar, ModMaster will continually poll all registers when it is running. While ModMaster is continually polling, you may also request a poll manually (e.g. you may have configured ModMaster to poll every 5 minutes, and you want to update the registers without waiting several minutes for the next automatic poll).
See Reading and writing registers for a description of how the reading and writing is implemented.
The Polling Settings control several aspects of how the polling is done.