Abstract: There is provided an initializing method for a programmable machine controller, whereby various control parameters of the programmable machine controller can be initialized quickly. The initial values of the various parameters, stored in a random access memory for initial-value setting of the controller, are transferred to a blank region of another random access memory for storage therein (S1.about.S4), and then transferred to a read-only memory (ROM) cassette for storage therein (S5). When a command for parameter initialization is delivered with the controller loaded with the ROM cassette, the various parameters are initialized using the initial values stored in the cassette.

Abstract: A signal tracing control system provided in a programmable machine controller (PMC) which controls a machine in response to a signal from a numerical control apparatus. A signal of a monitored RAM (1) is monitored for a change by a monitoring circuit (21). When a signal change is detected by the signal monitoring circuit (21), it applies a signal to a writing control circuit (22) which then writes the data of the monitored RAM (1) into a tracing buffer (2). This cycle of operation is repeated. Thus, only when a data item in the monitored RAM (1) is changed, is the signal traced. Effective signal tracing can therefore be effected with a small memory capacity.

Abstract: The present invention allows a programmable controller in a stored program system to easily execute even complex sequence control. A memory (50) has stored therein a first program of the ladder type and a second program described in another program language such as PASCAL or FORTRAN. First and second setting devices (51) and (52) set the execution times for processing by the first and second programs, respectively. A management device (53) executes the processing according to the first and second programs alternately for the periods of time set by the first and second setting device (51) and (52).