A communication system having a main control portion (MCP) to transmit information destined to a device n cascade levels down, and create an error detection code (CRC code) for data that contains a count of remaining cascade levels until an n-th cascade level and the information. The code is transmitted to an upstream sub-control portion (USCP) with the data. The USCP creates a CRC code for the data, and compares the created and received codes. For a match, the USCP determines whether the information is destined to itself based on the remaining cascade level count. When the information is not so destined, the USCP creates new data with the remaining cascade level count reduced by 1, and a CRC code for the new data, and transmits the created code to a further device, with the new data.