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Hi your are trying to establish serial communicaiton using IR modules, for this the above circuit is not appropriate. you should make some changes on that circuit
do one thing remove the first 555timer(left side) and connect the TXD pin of the 8051 to 4th pin of the second 555timer. Because the second (right side) 555timer is for to generate 38Khz frequency signal as a carrier. your data is message signal which is super imposed on 38khz signal and then transmitter via IR devices.
further more about the circuit go to
**broken link removed**