a151218 Posted December 18, 2008 Report Posted December 18, 2008 Hi..Everybody...I have a question about Aisj71uc24-R4(RS422/485)...I want to use Aisj71uc24-R4 connect modbus device(RS485)...So I edit program CRC by myself...When I test communication, I found a problem. I use RS485 so the SDA,RDA short and SDB,RDB short and connect to modbus device DATA + and DATA-. But when send data,I found the content of receive is the send data.I also ad 330ohm resistance between SDA,RDA and SDB,RDB and the condition is the same.Can anybody tell me how to solve the problem?
panic mode Posted December 18, 2008 Report Posted December 18, 2008 for multidrop connection rs485 can use one (m:n) or two pairs of wires (1:n). since you are using just one pair, input and output is looped back, there is no way to avoid reading what you send (check loopback section of manual)
a151218 Posted December 19, 2008 Author Report Posted December 19, 2008 thx panic mode......... I paste my wiring diagram.I test still found the content of receive is the send data. Before,I have had the experience of use Danfoss INV connect A1SJ71UC24-R4.It's OK and I can not receive my send date,only receive INV respond date.But now I test ,I can receive device respond data,besides receive my send date.Can anybody tell me how to solve the problem?
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