[time-nuts] Prologix GPIB/USB converter help...

SAIDJACK at aol.com SAIDJACK at aol.com
Tue Apr 17 19:14:36 UTC 2007


 
In a message dated 4/17/2007 10:28:31 Pacific Daylight Time,  
tvb at LeapSecond.com writes:

What are  some examples of
> RS-232 hosts that need to talk to GPIB test  equipment?  Old/retired laptops
> being used as dumb  terminals?  Legacy DOS apps that don't have any form of
> USB  support?  Both?
> 
> -- john, KE5FX


Hi John,
 
in our case (Jackson-Labs FireFox Signal Generator) we use the Signal  
Generators' internal RS-232 port to drive a GPIP HP power meter such as the  436 etc 
to do an automatic RF level calibration of the generator.
 
The Signal Generator becomes a GPIB host via it's RS232 port and a  modified 
version of the Abdul board and controls the RF Power meter (setting  
frequency, and other parameters in the meter, and reading the RF power from the  meter).
 
Later models of the Agilent power meter such as the E4418 series have a  
built in RS-232 port and can connect directly to our FireFox generator - a  simple 
null-modem cable does the trick.

These power meters don't have USB ports, and if they did, we would  have to 
have a USB host on our generator - a nightmare scenario for our  software.
 
So we get the best of all three worlds:
 
   * We ship a commercial RS-232 to USB adaptor with our  generator for users 
who don't have RS-232 ports on their PC's anymore, so USB is  fully supported 
and it adds less than $20 to the production cost of the  generator to support 
both USB and RS-232.
 
   * We can drive the newer Agilent power meters directly if they  have 
RS-232 ports (E4418 etc)
 
   * We can drive the older Agilent GPIB-only power meters such  as the 436 
using a modified version of the Abdul USB to GPIB board which  was modified to 
have a true RS-232 connector.
 
By the way: the biggest drawback of a USB port on an embedded system in my  
opinion is that users expect to be able to plug-in any type of device (USB HDD, 
 USB Memory Stick, USB Printers etc) and have them work magically. That 
doesen't  even work properly on Windows sometimes.
 
bye,
Said



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