(B, ) the utility model discloses a circuit of instrument and ground data intercommunication in pit including sending received signal select switch, sends received signal select switch's output and is connected through overvoltage crowbar and power data bus, send being connected all the way of received signal select switch through transmitting circuit and microprocessor, it is connected through receiving circuit and microprocessor to send another way of received signal select switch. The utility model discloses owing to adopted two binary encoding's technical scheme, can reduce the carrier level amplitude to 12~14 of current level amplitude. The utility model discloses can guarantee the level decay in 10000M's length range the amplitude be lighter than the carrier wave just the initial value 20%. And in certain bandwidth range transmitter data and do not need extra recovery time in succession, realized that the above continuous incessant coded data long distance of 128bit reliably conveys. Ideal effect has been reached. (B, )