Abstract: A programmable controller system includes at least one programmable controller and one or more other devices with which it can exchange data through a network or a bus. The programmable controller stores one or more program blocks and executes them selectively and individually by switching them between active and stopped conditions. At least one of the other devices is adapted to issue a command to have a specified operation carried out on a specified one of the program blocks. Upon receiving this command, the programmable controller carries out the specified operation on the specified programmable block and returns the result of the operation back to the device which issued the command. Such other devices may be themselves a programmable controller, a support tool or a host computer. The command may be to add or delete a specified problem block.

Abstract: A programmable controller has a function for referring to a reference clock signal every cycle time and updating the present value of a count in a user timer upon confirming that the reference clock signal has changed state. An execution time of a user program is measured from the start of execution thereof in each cycle time, and it is determined whether the measured execution time has exceeded a minimum unit time of the reference clock signal, such that the present value of the count in the user timer is updated even if the minimum unit time has been exceeded. As a result, the present value of the user timer count can be updated with certainty even if the user program execution time is so long that the minimum unit time is exceeded.