Relay unit for photoelectric sensor

1. A relay unit for photoelectric sensor that performs signal transmission between a photoelectric sensor and a communication master, the relay unit for photoelectric sensor comprising:

a first terminal to which a first cable is connected between the first terminal and the photoelectric sensor;

a second terminal to which a second cable is connected between the second terminal and a controller;

a third terminal to which a third cable is connected between the third terminal and the communication master;

a synchronization line which connects the first terminal to the second terminal and through which setting information and detection information of the photoelectric sensor is transmitted;

a sensor-side communication controller configured to communicate with the photoelectric sensor via a branch line that branches off from the synchronization line;

a master-side communication controller connected to and configured to communicate with the sensor-side communication controller and configured to communicate with the communication master via the third cable connected to the third terminal; and

a storage unit,

wherein the sensor-side communication controller acquires the setting information from the synchronization line and store the acquired setting information in the storage unit in response to reception of a backup instruction from the communication master by the master-side communication controller,

wherein the sensor-side communication controller outputs the setting information stored in the storage unit to the synchronization line via the branch line in response to reception of a restoration instruction from the communication master by the master-side communication controller,

wherein the sensor-side communication controller periodically or aperiodically compares the setting information transmitted through the synchronization line with the setting information of the storage unit so as to detect presence or absence of a difference, and

wherein the master-side communication controller outputs a notification signal to the communication master in response to detection of the difference.

2. The relay unit for photoelectric sensor according to claim 1 ,

wherein the sensor-side communication controller prohibits the setting information stored in the storage unit from being output to the synchronization line until the difference is resolved.

3. The relay unit for photoelectric sensor according to claim 1 ,

wherein the sensor-side communication controller notifies the communication master of recovery information via the master-side communication controller in response to resolution of the difference.

4. The relay unit for photoelectric sensor according to claim 1 ,

wherein the sensor-side communication controller is configured to prohibit, by authentication data, a function of outputting the setting information stored in the storage unit to the synchronization line together with an update flag, and

wherein the backup instruction and the restoration instruction from the communication master are not accepted during prohibition.

5. The relay unit for photoelectric sensor according to claim 1 , further comprising:

a transceiver configured to convert the setting information acquired via the branch line into a format interpretable by the sensor-side communication controller; and

an isolation unit configured to separately arrange a safety-related circuit and a non-safety-related circuit to electrically isolate the safety-related circuit from the non-safety-related circuit, the safety-related circuit comprising the synchronization line, the branch line, and the transceiver, the non-safety-related circuit comprising the sensor-side communication controller and the master-side communication controller.

6. The relay unit for photoelectric sensor according to claim 1 ,

wherein the communication master is an IO-Link master.

7. A relay unit for photoelectric sensor that performs signal transmission between a photoelectric sensor and a communication master, the relay unit for photoelectric sensor comprising:

a first terminal to which a first cable is connected between the first terminal and the photoelectric sensor;

a second terminal to which a second cable is connected between the second terminal and a controller;

a third terminal to which a third cable is connected between the third terminal and the communication master;

a synchronization line which connects the first terminal to the second terminal and through which setting information and detection information of the photoelectric sensor is transmitted;

a sensor-side communication controller configured to communicate with the photoelectric sensor via a branch line that branches off from the synchronization line;

a master-side communication controller connected to and configured to communicate with the sensor-side communication controller and configured to communicate with the communication master via the third cable connected to the third terminal; and

a storage unit,

wherein the sensor-side communication controller acquires the setting information from the synchronization line and store the acquired setting information in the storage unit in response to reception of a backup instruction from the communication master by the master-side communication controller,

wherein the sensor-side communication controller outputs the setting information stored in the storage unit to the synchronization line via the branch line in response to reception of a restoration instruction from the communication master by the master-side communication controller,

wherein the sensor-side communication controller periodically or aperiodically compares the setting information transmitted through the synchronization line with the setting information of the storage unit so as to detect presence or absence of a difference, and

wherein the sensor-side communication controller stores the setting information transmitted through the synchronization line in the storage unit in response to detection of the difference.