A counter variable search unit (121) finds a counter variable from a control program. A remainder calculation search unit (122) finds, from the control program, a remainder calculation for the counter variable. A branch instruction search unit (123) finds, from the control program, a condition branch instruction for a remainder of the remainder calculation. An input/output variable extraction unit (124) extracts an input/output variable from a branch destination block of the condition branch instruction. A target appliance identification unit (125) identifies a target appliance to/from which a value of the extracted input/output variable is inputted/outputted. A communication cycle determination unit (126) determines a communication cycle of the identified target appliance.