Message indicating a pass-through mode in which data is relayed between a terminal device and a network without being subjected to a conversion process

An information processing system comprising a host device, a first information processing apparatus, and a second information processing apparatus, wherein the first information processing apparatus comprises:

• a first device interface configured to transmit and receive data to and from a terminal device;
• a first network interface configured to transmit and receive data to and from a network;
• a power supply part configured to supply electric power from an external power supply;
• a battery configured to supply electric power when a power supply from the power supply part is stopped;
• and
• a first control part configured to:
• perform a first conversion process on data from the terminal device, and transmit the data to the network;
• and
• when the power supply from the power supply part is stopped, transmit, to the host device through the first network interface, a first message indicating that a pass-through mode in which data is relayed between the terminal device and the network without being subjected to the first conversion process is set, and set the pass-through mode,
• wherein the second information processing apparatus comprises:
• a second device interface configured to transmit and receive data to and from the host device;
• a second network interface configured to transmit and receive data to and from the terminal device through the network;
• and
• a second control part configured to:
• perform a second conversion process corresponding to the first conversion process on data from the first information processing apparatus, and transmit the data to the host device;
• and
• when a command indicating that the first information processing apparatus is operating in the pass-through mode, transmit the data from the first information processing apparatus to the host device without performing the second conversion process, and
• wherein the host device includes:
• a communication part configured to transmit and receive data to and from the second information processing apparatus;
• and
• a processor configured to transmit the command to the second information processing apparatus through the communication part when the first message is received through the communication part.