On Thu, 2012-03-22 at 16:37 +0200, Viesturs Lācis wrote: > 2012/3/22 Greg Bernard <yankeelena2...@yahoo.com>: > > Do you have a usb to ttl converter? If so you could use a terminal program > > and do a loop-back test (connect RX to TX) > > No. > The converter I built is the very first scheme here: > http://www.kmitl.ac.th/~kswichit/Rs422/Rs422.pdf > > Viesturs
I think you should be able to do a loop back on the SN75179. The first schematic shows only a TTL to differential converter. The rest of the schematic shows a differential to RS-232 converter, which I assume does not apply here. Anyway, on one side of the chip the RxD and TxD pins could be tied together, then a signal on A(pin 8) and B (pin 7) should be mirrored on Y (5) and Z (6). In other words, ground (with a resistor) B and pull A up with a resistor to +5. Y should go up towards +5 and Z towards ground. Switch the ground and pull up on A and B, and Y and Z signals should switch. One could also loop the differential side of the chip by tying A to Y and B to Z (I think). Pull up or ground TxD, and RxD should follow. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA ------------------------------------------------------------------------------ This SF email is sponsosred by: Try Windows Azure free for 90 days Click Here http://p.sf.net/sfu/sfd2d-msazure _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
