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RS-485

Question asked by Lisa Fu on Jun 18, 2012
Latest reply on Jun 19, 2012 by Lisa Fu

Hello, 

I use CW10.2, MQX 3.8 and TWR-K60F120M tower demo system. I would like to implement RS485. I have seen that there is demo example come with MQX which is at C:\Program Files\Freescale\Freescale MQX 3.8\mqx\examples\rs485. I have built this project, but I can’t see any data from Clear Terminal which is connected to my PC RS-232 port. 

I set jumpers on TWR-SER board to make J15 as RS-485 (instead of RS-232) according to TWR-SER User Manual. I have defined BSPCFG_ENABLE_TTYF and BSPCFG_ENABLE_TTYB to be “1” at both user_config.h and twrk60f120m.h. (I check schematics of TWR-K60F120M, TWR-SER and tower boards, it looks like UART1 is connected to J15 of TWR-SER. If I am wrong, please point out to me. Thanks!). I also set BSP_DEFAULT_IO_CHANNEL to be “ttyf:”. I use SENA LTC100 RS-232 to RS485 converter connecting to J15 of 
TWR-SER. I can see print out with printf() from both P&E Terminal Window (which I believe is connected to UART6) 
and Clear Terminal which is monitoring RS-232 port of my PC and the other end is UART1 of demo board. 

 

I have also tried ITTYB, there is no luck. 

What I have missed? Why it doesn't work? I use CW10.2 debugger to debug this rs485 demo program, it looks like 
that write() function is not successful. Please help me to identity this problem. I guess the problem is on software, not 
hardware. 

Thanks! 

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