8051 interface with max485

[srinu_gonuguntla]

max485

hi,
i am using max 485 to communicate with meter.
problem is i am unable to send my data through max485.
my max485 ic pin voltages(i am using 485 as half duplex)

R0 = 4.7V
DE&RE/ = 0.6V
DI = 3.0V
VCC =5V
GND
A&B = 0.6V

WHY i am not getting data what i have send from 8051 to hyper terminal.
(i am using hyperterminal for testing whether communication is working or not).
i am using baud rate 9600.

please help me.

 

[stefanSK]

8051 max485

sequency of program for send one BYTE:

1. jnb TI,$ ; wait for finish last transmit
2. setb DE&RE ; enable RS485 transceiver for send
3. mov sbuf, byte_to_send
4. jnb TI, $ ; very important!!!!! wait for trasmit whole BYTE
5. clr TI
6. clr DE&rRE ; enable receive

noteins 1 & 2 shorted

 

[srinu_gonuguntla]

max485 8051

actually i am sending only one charecter only.
contineously i am sending same character but i am not getting any thing.
any way thak's for responce.