[Soekris] serial port on 4501

[Soren Kristensen]

Hi,

Henry Spencer wrote:
> On 16 Apr 2003, Rahul Kalaskar wrote:
> 
>>The problem seems to operation of serial port on net4501. The serial
>>driver  (/proc/tty/drivers/serial ) says that the RTS and DTS lines on
>>the serial port are on. But, on connecting a RS-232 line analyser, I
>>find that none of the lines are on. In fact, I measured the voltages on
>>the serial lines. None are carrying any voltages...
> 
> 
> A possibly-relevant comment from Soeren in late November last year:
> 
> "The net45xx series manufactured until about 2 months ago had the RS232
> transceiver configured in a auto power saving mode where it turned
> itself off if there isn't any active inputs...
> Older boards can be modified by cutting the thin trace from U5 (MAX3243)
> pin 23 to the capacitor next to it, and instead connecting pin 23 to pin
> 22 with a solder bridge.
> The updated boards are net4521 dated 020922, net4511 dated 020922 and
> net4501 dated 020910."

One comments to add, I actually made an error ordering PCB's, so on the 
net4501 that update was not until ver 6 PCB's dated 030319, which has 
not started to ship yet....

So unless Rahul has cable issues, he could be seeing the issue with the 
RS232 transciver in power down mode. But shouldn't the UPS provide valid 
RS-232 levels ?


Soren


>                                                           Henry Spencer
>                                                        henry at spsystems.net
> 
> 
> 
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