I bought this RS232-TTL converter https://www.digikey.com/product-detail/en/seeed-technology-co-ltd/101990008/1597-1306-ND/5487765
and I'm using this along with an Arduino Mega 2560
I'm feeding the Arduino using this dc-dc converter directly to a 5[V] pin (i know this is not recommended and using a dc-dc is advised) https://www.digikey.com/products/en?keywords=pyb10q24s5u
The DC-DC is feeded by a 12[V] - 12[A] DC power supply.
The same DC-DC is used to feed the rs232-ttl module
-2400b 8 bits 1 sb np. -PC > USB cable > Arduino(usb powered) > RS232-TTL module(powered by the Arduino)>RS232-USB>PC(com8)
->sometimes it works:
Vcc = 5[V] V+ = 8 [V] V- = -8 [V] C1 and C2 oscillate. communication** works
-> and sometimes it doesn´t.
Vcc= 5[V] V+= 4[V] V-=0.6 [V] C1 and C2 not oscillating. Communication** not working.
EDIT: if i send a character from the PC, it starts to work, which is not a desired behavior.
EDIT2: same behavior with the Arduino out of the picture)
Now, using the intended connections .
(usb cable not connected) PowerSource>DC-DC>Arduino(powered by dc-dc)>RS232 module (nothing connected)
Vcc= 5 [V] V+= 4 [V] V-=0.6 [V] C1 and C2 not oscillating. Communication not working heats
Same connections, using loopback:
Vcc= 5 [V] V+= 4 [V] V-=0.6 [V] C1 and C2 not oscillating. -Rx at 3 [V] -Tx at 3 [V]
Same connections, connected to pc
Vcc= 5 [V] V+= 4 [V] V-=0.6 [V] C1 and C2 not oscillating. Rx out: at 3 [V], when a signal is sent from PC, it goes from 1 [V] to 4[V] then goes back to 3 [V] Tx out: nothing
i've been trying everything, i bought 6 RS232 modules and tried 3 so far, all of them have the same symptoms
EDIT: well, the RS232-TTL works IF a signal comes from the RS232 side first (ie:PC or Modem), if the TTL part does Tx first (ie: Arduino), the max3232 will heat and it becomes unusable, it seems to be a problem with the low power mode. And that is all, no solutions, just a work around.