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Can't talk to E3633A over E5805A USB to RS232

Question asked by EricPeterson on Apr 1, 2010
Latest reply on Apr 13, 2010 by chunhlow
I have a Dell XPS 630 workstation running Win XP sp3 and an Agilent E5805A USB  to 4-port RS232 extender through one port of which I’m trying to remotely control an E3633A. The E5805A configuration utilities come up and identify the box and have configured the 4 ports as COM3 through COM6. System driver and E5805A configuration utility interfaces both indicate the 4-port device is working properly.

Agilent Connection Expert Version 15.1.12008.0 identifies the power supply as IDN string: HEWLETT-PACKARD,E3633A,0,1.7-5.0-1.0 . I’m able to send commands and receive responses with the interactive I/O window. Sending “SYST:VERS?” for example, gets me “1996.0«x0D»” in the display. Using “SYST:REM” followed by “APPL 5.0 , 1.0” gets me the power display output activated at 5 v and 1 A, as expected. Sending “*TST?” gets me a response of “+0«x0D»” . After sending the system remote the front panel is disabled as it should be.

However, “OUTP OFF” doesn’t seem to do anything.  “*RST” does function, which would allow me to overstep the failure of the output off command in my system.
In my app I’m using an older windows API communications library from Willies Computer Software Company, COMM-DRV/Lib. C based. My application development is C++ in Visual Studio 2008, a combination I’ve used on three or four other projects, and one that’s always worked flawlessly. Its calls are reporting good serial communications configuration within the app. The comm library initialization parameters are:


… which are self-explanatory and which match the parameters of the table of page 64 of the manul plus the power supply settings. The I/O Config button on the supply front panel shows me 9600 BAUD and NONE 8 BITS, and page 66 of the device manual tells me that the handshaking is set to DTR+DSR, which is what the comm library’s “PROT_DTRDTR” option selects. However, I’ve also tried COMM-DRV/Lib’s PROT_NONDTR option, which selects remote device DTR+DSR protocols but none at the computer’s end. The results are the same for both choices. The single start bit is an RS232C standard and is configurable neither on the power supply nor within the communications library.

When I issue ASCII strings via the communications library RS232 interface, only “SYST:REM” fails to generate an error on the power supply side. “SYST:VERS?” kicks the power supply’s ERR light on. So do “APPLY 5.0 , 1.0” and “OUTP ON”.  Interogating that error from the front panel shows me an error -113, “Undefined Header”. The description of this error mentions incorrect short forms of commands as a possible problem… so I tried complete commands like “SYSTem” and “APPLy”. These don’t generate any errors… but neither does anything happen at all. There is no response to any interogation command in any case.

Clearly, either I’ve missed something in the setup or there’s a problem between the communications library and the Agilent E5805A. I’m looking into that too. Anything obvious stand out here?