1. A diagnostics agent to be used with an execution code and an indicator, the code for controlling control mechanism sets which in turn control resources to perform an industrial process, the code controlling by providing sequential resource requests to the mechanism sets, at least a sub-set of requests including sequential events, the agent for providing a status based diagnostic output and comprising: for at least a subset of requests, status based diagnostic code interspersed among the execution code indicating request specific events; a processor for monitoring events as they occur; and a driver linked to the processor and the indicator for, as the execution code progresses, indicating the next event expected to occur.