The disclosure discloses a reservation method and apparatus for an electronic device for improving reservation accuracy, wherein the reservation method includes: receiving a reservation instruction sent by a terminal device, wherein the reservation instruction carries identification information, an operation content, and an execution time of the electronic device; obtaining a current time from a clock source and starts timing, and obtaining a target reference time, wherein the clock source is a clock source of the terminal device, a network device, or the reservation apparatus, and the target reference time is configured to indicate the time after timing; and if determining that a difference value between the target reference time and the execution time is less than values within a preset range, controlling the electronic device to execute the reservation instruction.

A process control system includes: a controller; at least one input and output module connected to the controller; and an allowable propagation delay value calculator in the controller, the allowable propagation delay value calculator being configured to calculate, based on the number of input and output modules connected to the controller, an allowable range for propagation delay time between the controller and the input and output module.

A process control system includes: a controller; at least one input and output module connected to the controller; and an allowable propagation delay value calculator in the controller, the allowable propagation delay value calculator being configured to calculate, based on the number of input and output modules connected to the controller, an allowable range for propagation delay time between the controller and the input and output module.

The disclosure discloses a reservation method and apparatus for an electronic device for improving reservation accuracy, wherein the reservation method includes: receiving a reservation instruction sent by a terminal device, wherein the reservation instruction carries identification information, an operation content, and an execution time of the electronic device; obtaining a current time from a clock source and starts timing, and obtaining a target reference time, wherein the clock source is a clock source of the terminal device, a network device, or the reservation apparatus, and the target reference time is configured to indicate the time after timing; and if determining that a difference value between the target reference time and the execution time is less than values within a preset range, controlling the electronic device to execute the reservation instruction.