HP 165xx analyzer cards threshold level

• HP 165xx analyzer cards threshold level
  Posted by davorin on 24 Jan, 2015 22:42
• Evnon' (o;
  
  One question popped into my mind lately...if it is possible to use for example the 16510B or 16555A cards to analyze RS232 level signals...
  
  For example the 16555A datasheet mentions that the pod input level can be 40V peak-peak....and the threshold level can be set between -6V and +6V...
  So theoretically I can just set the threshold just to 0V and directly hook up to RS232 signals?
  
  I guess decoding the stream is out of question (o;
  
  
• #1 Reply
  Posted by helius on 24 Jan, 2015 23:20
• Quote from: davorin on 24 Jan, 2015 22:42

  I guess decoding the stream is out of question (o;
  

  There was some discussion of protocol decoding software in an old thread:
  https://www.eevblog.com/forum/testgear/hpagilent-16500b-software/
  
  tldr; there was a MS-DOS development package that created "inverse assembler modules" that you could then load on the 16500. I guess that could be used for serial protocols too, but I don't really know.
  
  All things considered it would be much easier to just get a Bus Pirate for serial protocols
• #2 Reply
  Posted by BloodyCactus on 26 Jan, 2015 14:23
• there are dissasemblers 'inverse assemblers' around to display the decoded streams.
• #3 Reply
  Posted by davorin on 26 Jan, 2015 14:47
• Okay..thanks (o;
  
  But my primary question was more about the levels I can feed into the analyzer cards...
  
  
• #4 Reply
  Posted by mike_kawasaki on 26 Jan, 2015 18:15
• Quote from: davorin on 26 Jan, 2015 14:47

  Okay..thanks (o;
  
  But my primary question was more about the levels I can feed into the analyzer cards...
  

  
  This is going deep into my memory (my first job at HP, 26 years ago, was the Product Support Engineer for the 16500 and 1650)...
  
  * Yes, a RS-232 signal can easily be managed by the 16500A acquisition cards.  The threshold can be set to +/- 9.9V with .1V increments; while the dynamic range is +/-10V from threshold.  Although RS-232 swings to +/-12V you are really just focused on the threshold level.  As you noted the max voltage is +/-40V.
  
  * The debugging/disassembly was done through a bus interface 'preprocessor'.  The model number is a 10342B and maybe can find one on the used market very cheap.  The 10342B basically converted different bus interfaces to the logic analyzer pods; plus the configuration software and the disassembly software.  I think it converted RS-232, RS-449 and HP-IB.
  
  Hope this helps!
  
  Mike
  
  
• #5 Reply
  Posted by davorin on 26 Jan, 2015 18:21
• Hello Mike
  
  This helps me perfectly...many thanks :-)
  
  Well..inverse assembly is not a current option....more important was the fact that I could connect one pod to rs232 levels while the other goes to TTL/CMOS levels...all coming from the same board...this saves me of hooking up a DSO in parallel...
  
  
• #6 Reply
  Posted by PlainName on 26 Jan, 2015 21:10
• Quote

  So theoretically I can just set the threshold just to 0V

  
  Yes, but note that RS232 levels are +3V to +25V and -3V to -25V. There is a band of hysteresis between +3V and -3V - it would be possible to have a dodgy signal which would look fine when sampled at 0V without hysteresis.
  
  Having said that, practical experience suggests that real kit will handle seriously dodgy signals just fine, so...