RS485 problem on XBee-PRO XSC S3B

Hi, I have a problem on enable RS485 on Xbee-Pro XSC S3B 900Mhz.

I don’t have this problem on Xbee 2.4 GHz.

In X-CTU, Modem Configuration Page is
Modem: XBP9B-XC
Function set: XBee-Pro XSC (S3B) 9600 920 MHz
Version: I tried both 3209 and 320C, not work

In Serial Interfaceing
CS-DO2 configuration : 3-RS485 TX enable high

My problem is PIN12 is always high after power on. Therefore, Xbee can not receive Data via RS485 communication from computer but it can get data from another Xbee.

PIN12 will be low after it get data from another XBee. And it works perfect after that.

After power on I did not send any data why PIN12 always high.
Please help thank you

After several try, finally I fixed the problem by update to firmware version 3211.


I have a problem with this xbee I can not configure what values ​​are configured, for the XBEE PRO S3B XBP9B-DM I have no problem but for the XC I can not configure it the filmware is 3214