Hi shriram first of all i guess your zigbee module is connected to the PC through serial port.In that case you can use the serial port class in matlab.using it is quite easy.first create a serial port object as follows
serPort = serial('comPort','Baudrate',57600,'DataBits',8,'Parity','none','StopBits',1);
here comPort(within single quotes) is the serial port to which zigbee module is connected.all others are self explanatory
fopen(serPort);
fwrite(serPort,128,'uchar');
fwrite(serPort,132,'uchar');
fclose(serPort);
here 128 and 132 are values transmitted as unsigned char.once char is transmitted close the port coz otherwise it can cause timeout or you can specify a large timeout value when you create serial port object itself
also make sure that your zigbee modules are configured properly(check with appropriate user manual for your modules)