Emax

well, it starts to make sense! it really looked disappointing, now there are new things to check. 

meanwhile i switched to an Emulator II+HD to do the tests, because i know that works well with SD thru DB25. is it fair to assume that it has a healthy port and will work with the EMXP too?

i put this back to the bench and will check if there were any signals coming in and out on the TX-RX stuff. i havent included the LEDs on this design.

since the UA9637AC is not available around, i replaced it. i did not use any capacitors and resistors though. i assume you used it to shape the signal (apart from those to support the LEDs). if there were any other reasons, please let me know, i need to check that.

i am going to list the short description of my version in a very easy way. everything is connected direct, no resistors or capacitors used. please see below if you were interested in.

"So, what error do you actually get in EMXP ?   "

When receiving from the EII it says: Errorcode 990. There is a communication problem with the EII. ReasonCode is 3.

i am going to post it quick, so maybe you had more time to check and think, and now i'll return to measure the circuitry.

and now the connections:



RECEIVER (RX): MAX RS485
---------------------
TXD+ (Emax: pin8) -> Teensy RXD+ (RS422:3) -> RS485:7 (B)
TXD- (Emax:pin9) -> Teensy RXD- (RS422:4) -> RS485:6 (A)
GND (Emax:pin3) -> Teensy (RS422:5) -> RS485:5 (GND) 
RS485:pin1 (R0) -> Teensy PD2 (RXD1)
RS485:pin2 (NRE) -> L 
RS485:pin3 (D) -> L  
RS485:pin4 (DI) ->  not connected 

TRANSCIVER (TX): MAX RS485
------------------------
Teensy TXD (PD3) -> RS485:pin4 (DI)
RS485:pin6 (A) -> Emax:pin5 (RXD-)
RS485:pin7 (B) -> Emax:pin4 (RXD+)
RS485:1 (R0) -> not connected
RS485:2 (NRE) ->H
RS485:3 (DE) ->H

CLOCK (CLK): SN75176B
------------------------
CLK (Emax:5) -> SN75176B Pin6 (A) 
SN75176B:pin7: B -> L
SN75176B:pin1: R -> Teensy PD5  (XCK)
SN75176B:pin4 (D) -> not connected
SN75176B:pin3 (DE) -> L 
SN75176B:pin2 (NRE) -> L