Output uses

[Marty]

I have done a little searching but I'm not finding exactly what I'm looking for; hoping someone can link me or provide some knowledge.
I'm not clear on the P259, S259 etc outputs and when they "should" be used, and when they are "options".
Hoping to find a response something like
P259 are low current outputs, and can be used to trigger relays or...
(/\/\/\ not sure that's a good description but hopefully that gets the question across)

I'm Finishing up the last of my wiring, and building a flying lead harness for the EC-18. just contemplating which of the outputs I might find useful.
I have 1 analog channel chosen for an LED bar gauge for A/F, set up for a 0-5v. All others are open!
Thanks,

Marty

[stroft]

InjGroup - 7A - injector output
I259 - 7A - ignition output
S259 - 1A - stepper
P259 - 350mA - low current output

Ignition outputs have best protection, P259 weakest.

[mattias]

If you check the "assign outputs" visual dialog in VemsTune, each output has it's current capacity mentioned. That gives a good hint at how you can use them.

Personally I never use the P259 low current output to drive anything. Ok, maybe a LED or two and maybe the rpm gauge (EC36-pin3 has an internal pull-up for this purpose) if I have no free S259 stepper outputs. Never use it to drive solenoids (=relays), chances are that eventually the flyback voltage will kill the output and the chip itself will draw enough current to drain the +5V regulator that also supplies power to the VR trigger chip (LM1815) - basically stopping your car dead in it's tracks if you have a VR based trigger. ECU surgery needed to cut the +5V pins on the P259 to get by, and move the outputs used on the P259 to other free  outputs - recommend the I259 ignition driver outputs (they handle "anything").
Of course, you can always add protection diodes on each output.. but why bother when there are other free outputs?
Ironically most drawings make it clear to use the P259 to drive the fuel pump relay.

[gunni]

I on the other hand always use the P259 outputs to run relays and haven´t had one cause a problem to the chip.

But I reccomend that higher current outputs are used first if possible.

[GintsK]

I use P259 outputs for driving automotive relays with no issues. As a rule those relays contain elements what suppress flyback voltage spike: diode or simply resistor in parallel to coil.
P259 chip usually fails because of voltage offset between power and electronics grounding. Or when cheep Chinese relays are used.

Gints

[mattias]

I have had the P259 fail even with the v3 harness relays, I rest my case - you can do as you please.

[Sprocket]

I have had the P259 fail even with the v3 harness relays, I rest my case - you can do as you please.

I know this is old, but i'm just getting back into this.

The quote above brings into question the purpose of the P259 chip? If all you can drive are LED's and lamps. Is there a real need to drive 8 LEDs or lamps in any application? why have the developers not introduced a more robust circuit or chip? I don't think it is a real problem so long as certain guidelines are followed and not strayed from. I totally understand why you may not want to use it after failures.

I personally have used the P259 for driving relays and indicator lamps, but as already discussed, automotive relays with flyback protection inbuilt, particularly the Siemens items with the yellow case (flyback diode clearly indicated on the schematic on its case). I also use the OEM multi function relay that Rover use on all their MEMS controllers, again those have inbuilt flyback protection resistors (again clearly indicated on the Rover wiring schematics). I have probibly done 15,000 miles using those relays on the P259, not much in the grand scheme, but its enough for me to be confident with it for how I use the car. I'm not convinced the Webshop relays have inbuilt flyback (no detail of the relays talked about), which may or may not contribute to the percieved problem.

I know the cheap black auomotive relays available in many accessory shops do not have inbuilt flyback protection, and the one available in the webshop looks dangerously similar. Not saying it is, but there isnt anything to say that it is not.

As it happens, I have also suffered a P259 failure, but that was most certainly down to a grounding issue (because I stupidly and knowingly created the problem ), and not as a result of the relays.

Output use is detailed here http://www.vems.hu/wiki/index.php?page=GenBoard%2FManual%2FDigitalOut%2FTable