Problem getting M4 to comunicate over rs232

[Kalns]

Hello.
I have an M4 serial4631 and I cannot get it to work EMP shows not connected.

Laptop has physical com port, I made a dualboot system so freedos would load seperately of windows.
I have tried few diffrent versions of EMP, 6.12 / 6.13 / 6.20d
Should I have to configure baudrate and other comunication settings beforehand, or defaults should work ?
I tried also dosbox to run it, but it does not connect to ecu, so I am starting to wonder if the ecu itself is alive?
I measured if it gives out +5v on pin4 and it does

In your experience, have there ever been an error with the ecu itself ?

[SprinterTRD]

Are you using a MoTeC PCI cable? If not then that is your problem.

Sorry just noticed the Serial which does not require the cable however the D9 connector from the ECU needs to be wired for a NON PCI setup.

[Kalns]

I am folowing user guide https://www.motec.com.au/filedownload.p ... docid=1086
So I connected pin11 to pin5(gnd) pin21 to pin2 (Rx) and pin22 to pin3(Tx)
Since submiting topic I have also installed dosbox on windows 10x86 and configured it, but still it does not connect to ecu. EMP just shows in upper right corner ECI Not Connected.
Should I use all 8 pins to get the coms working ? Like null modem cable ? All serial devices that I have used, usualy need only these 3 pins..

I am considering to install xp on my laptop just to test if there is some glitch in freedos serial port interpretation.
I know the port works in windows because I did a terminal test between two computers on it..
Strange think is that even when i boot freedos and run thesame EMP6.2d it does not connect ..

Yes I have tested the power, ecu has +12 between pin1 and pin 25, I am benchtesting it at the moment.

[Stephen Dean]

Hi,

For Serial communications, the wiring needs to be like this.

M4 RS232 Serial Wiring.png (24.86 KiB) Viewed 24555 times

[Kalns]

Thanks, got it working.
Oddly enought this info is nowhere to be found..

With computers physical com1 it did not work, but with prolific usb to com cable it works fine in dosbox

Thanks for input.