Question for my safety planning
Hi all,
I'm using a PDM25 as the central control and logic unit in an EV conversion — it drives the HV contactors and passes on shutdown commands from a separate BMS via CAN.
Mine is the earlier revision (it came with the PDM 15/25 manual, not the newer 15/25/35 one), so I'd like to confirm a few behaviours against the right hardware before I finalise the safety design.
Three questions:
If the processor hangs or locks up while the unit is still powered, what happens to the outputs — do they hold their last commanded state, or switch off? I'm trying to work out whether a locked-up PDM could leave an output (and therefore a contactor) energised.
Is there any internal watchdog or fail-safe that switches the outputs off if the processor stops running normally? Or would I need to add an external heartbeat for that?
Can the PDM's own 12 V supply voltage be used as a variable in the logic (Functions/Maths) — for example to inhibit an output below a set voltage? And what's the input measurement range on this revision — can an input read ~12 V directly, or is a divider needed?
Thanks in advance — much appreciated