PURPOSE:To provide a portable logic simulation analyzing device which can conduct a confirmation test even when a computer for plant control is in on-line mode and analyze whether logic is true or false. CONSTITUTION:The computer 5 for plant control controls a plant into an expected state with information obtained from the plant and a logical operation expression for placing the plant in a specific control state. The logic simulation analyzing device 1 can be connected to the computer 5 for plant control through a cable 3. The logic simulation analyzing device 1 stores the simulation data and specific table of the logical operation expression in the control computer in the RAM in a housing 1 by interchanging information with the computer 5 for control, and simulate the logical operation by a CPU by using the table data and logical operation expression obtained from the RAM to decide whether the operation result is correct or not, thereby displaying the result on a display 15. The logic simulation analyzing device 1 has the small-sized display 15, a keyboard 16, a disk drive device 17, and other processing elements in the portable housing 11.
