A power line 
broadband carrier communication module networking test 
system of a built-in programmable attenuator comprises a 
power module, a 
broadband power-line carrier 
route module, a 
processing unit and networking units; the 
processing unit is connected with the 
broadband power-line carrier 
route module, the broadband power-line carrier 
route module is connected with one networking unit through a shielding 
radio frequency line, the rest networking units are in 
cascade connection with other networking units for networking through other shielding 
radio frequency lines, and the 
power module is connected with the networking units; the networking units are provided with multiple carrier modules, each carrier module is connected with a 
single chip microcomputer, and programmable attenuators which can conduct controlling through the carrier communication method of the programmable attenuators are arranged in the networking units, so that the replacement of the carrier module can be convenient, the 
system setting is not affected, the sizes of attenuation values and 
carrier signal route directions of communication nodes can be controlled, computer adaptive networking is achieved, 
client programs such as an 
ammeter or street lamp control or smart home can be written in the 
single chip microcomputer, and network tests used for various applications are achieved.