Line switching device

A line switching device comprising:

• a first switching device that includes:
• a plurality of first input ports to which first signals are input;
• and
• a plurality of first output ports, and
• a second switching device that includes:
• a plurality of second input ports to which second signals are input;
• and
• a plurality of second output ports, and
• a generator that generates timing pulses indicating periodic timings, wherein
• the first switching device further includes a first switch
• that includes:
• a write unit that writes at first timings that are based on the timing pulses generated by the generator, setting information for a signal that is to be switched to one of the first output ports;
• and
• a read unit that reads at second timings that are based on the timing pulses, the setting information written into a memory by the write unit, wherein the read unit temporarily suspends reading of the setting information when the timings indicated by the timing pulses have changed, and
• that selectively outputs, among the first signals input to the first switching device through the first input ports and branched signals branched from the second signals input to the second switching device through the second input ports, the signal to one of the first output ports indicated by the setting information read by the read unit, and
• the second switching device further includes a second switch that selectively outputs, among the second signals input to the second switching device through the second input ports and branched signals branched from the first signals input to the first switching device through the first input ports, a signal that is to be switched to any one of the second output ports of the second switching device.