Control system, control program transmission method, and recording medium

A control system comprising:

• a programmable controller to control a device;
• and
• a program transmission apparatus to transmit a control program for causing the programmable controller to control the device,
• the program transmission apparatus including
• program acquiring circuitry to acquire the control program,
• first code generating circuitry to generate, in response to issuance of a transmission instruction for the control program from one user of a plurality of users that is a user of the control program, a first code from (i) the control program and (ii) predetermined data that corresponds to the one user by a predetermined procedure, the first code being for verification of presence or absence of a change from the control program, and
• a transmitter to transmit the control program and the first code,
• the programmable controller including
• a receiver to receive the first code and a receiving program as the control program transmitted by the transmitter,
• second code generating circuitry to generate, by the predetermined procedure, a second code from (i) the receiving program and (ii) the predetermined data that is shared in advance with the program transmission apparatus and that corresponds to a specific user of the plurality of users,
• collator circuitry to determine whether the first code generated by the first code generating circuitry of the program transmission apparatus is identical to the second code generated by the second code generating circuitry of the programmable controller, and
• executing circuitry to execute the receiving program when the first code generated by the first code generating circuitry of the program transmission apparatus is identical to the second code generated by the second code generating circuitry of the programmable controller.