Auto RS232

[BC SYSTEMS]

Hi,

I have a problem trying to send serial a string out of the rs232 port of my test PC ( Nano and auto 485).  When trying to send a command the device does not respond.  I have checked the string coming out of the Nano with a serial sniffer and it is correct.

If I use my PC serial port or a FMD88 with the same command all is fine, the command is received and all works well ...

The serial device only has TX RX and GND so no RTS etc.  (I did try the RTS jumper in manual with different pot settings for good measure any way)

I guess this is a character timing issue??  Baud settings etc are all correct..... Any Ideas?

Cheers

 

[support]

The Auto-485 should be put in "Auto" mode since your RS232 device does not handle RTS.

When the Nano-10 send out data, is any of the LED on the Auto485 blinking?

Are you able to use a Hyperterminal software that runs on the PC to monitor the Nano-10 output data through the Auto485 and PC's RS232 port?

The best way to test is to first stop the Nano-10 from sending out data via COMM1. Then connect the PC to the Nano-10 via the USB-RS232 adapter and then Auto485. You should be able to use TLServer to send command to the Nano-10 and get a response from Nano-10. If this is successful then the Auto485 is working properly.

[BC SYSTEMS]

Hi,

Yep both TX and RX are fine.  Regarding the message, I'm sending the following via the print statment.

PRINT #1 "FOPEN MP.CSV"+CHR$(13)+CHR$(10) ;

The device requires CR and NL and that is the only way I could both terminators working.  (confirmed OK by the FMD??)

I will try Hyper termial and report back.  Its got me stumped!

BTW cable pinout:

2 - 3
3 - 2
5 - 5

Cable earthing is good between devices....

Cheers

[BC SYSTEMS]

Hi,

It looks like the problem is due to the Auto485 only creates a half duplex RS232 port.........

When we use the TMD or FMD they have full duplex RS232 ports.

Is there anything I can do about this??  i.e convert my half duplex  RS485 to full duplex RS485 with another IC??

Cheers

[support]

The 2-wire RS485 is inherently half duplex and there is no way to convert it to full duplex unless you are tapping into the IC pins of the RS485 driver chip (you could kill the CPU pin if a wrong voltage is connected to the pin so we are not recommending it)

It is probably simpler to just use the FMD88-10 to get your full duplex RS232 port.

Although if the communication between the PLC and your device is a command/response format, it should work with half duplex protocol. However, I don't know enough about your device to draw any conclusion but assuming that you have carried out enough testing to ascertain that a full duplex communication is required, then it is better to use the FMD88-10 or T100MD888+ PLC.