An automatic round or roll baler control system includes a microprocessor controlled signal processing circuit responsive to signals derived from various switches for controlling the wrapping of a bale and signalling to the operator the status of the baler. A diagnostic program may be initiated by the operator from a control panel. An operator's manual of instruction leads the operator through successive test steps such as, for example, actuating switches, and the signal processor visually and audibly signals the operator as to whether or not the test step was successful.