In one embodiment, a computer-implemented method includes executing firmware including a command list configured to maintain commands executable by a host processor of a field-programmable unit. One or more of the commands define communications between the host processor and one or more back-end processors of the field-replaceable unit. The command list includes both periodic commands representing periodic processes and non-periodic commands representing non-periodic processes. Each command in the command list is set to one of active mode and inactive mode. Executing the firmware includes cycling through the command list, and executing, by the host processor, only the commands in the command list that are set to active mode while cycling through the command list.