OK, I am picking a nit here, but it is an important one.
Â
Only one device in a system can be system controller. The SYSTEM controller is never passed. ACTIVE control can be passed. This grants permission for the active controller to assert the ATN line. However, the system controller retains control of the interface clear hardware line, and I believe also the REN line (remote). Asserting the ifc line will clear bus traffic, but will also return active control to the system controller.
Â
If there are two active controllers you find that one is constantly driving the ATN low and the other attempting to drive it high. This causes current flow that can potentially damage cards, and will definitely cause unreliable bus traffic. Whether it works will depend on a lot of factors like relative cable length and the number of devices loading the bus.Â
Â
Short answer, don't do it.
Â
However, back in the day we used to simply turn off the controller we weren't using. A GPIB system will work if at least 1/2 of the devices connected are powered up. We also used to violate the total length and the having a load every meter rules as well. The 16 max devices was a hard rule though and attempts to exceed that would cause the bus to fail.
Â
Jay Nemeth-JohannesÂ
Smart Sensor SystemsÂ
720 SW 14th Street
Loveland, Colorado 80537
(970) 663-0006Â (Office)
(970) 290-9797 (Cell)
HYPERLINK "http://www.smartsensorsystems.com/"www.SmartSensorSystems.com
Â
 _____ Â
From: Street, Andy M [mailto:andy.street@tycoelectronics.com]
Sent: Thursday, September 07, 2006 6:28 AM
To: VRF
Subject: RE: [vrf] GPIB question...
Hi Doug et al,
Â
Warren is correct - only one person can be the boss at any given time. In others words, GPIB only allows for one system controller at a given instant. I am not too sure what your ultimate goal is with all of this, but it may be worthwhile considering GPIB via LAN. Either use a dedicated GPIB/LAN box such as an E5810 or use a PC equipped with a GPIB interface and configure as a LAN server (this could be the existing PC). Basically your laptop (hooked to the PC with the GPIB resource via LAN) and the PC itself use the same GPIB resource. Issue is that you will have to manage any contention i.e. you want to control instruments whilst the script is doing stuff with them. GPIB-LAN server has been available in IO libraries for a long time.Â
Â
Andy
 _____ Â
From: Pickles, Warren [mailto:Warren.Pickles@tycoelectronics.com]
Sent: Thursday, September 07, 2006 3:17 AM
To: VRF
Subject: RE: [vrf] GPIB question...
Doug,
Â
I've never done anything like that, but I think this is how it's done: Only one device on the GPIB can be the controller; usually this is a PC sending commands to instruments. To do what you want to do, you have to pass control between the two PCs. You need to know the GPIB addresses of the two PCs (they must be different), and then you execute a pass_control command from the controller PC to the other PC. From VEE you do this with I/O, Advanced I/O, Interface Operations, then configure a transaction appropriately.Â
Â
Regards,
Warren
 _____ Â
From: Douglas Rudrow [mailto:drudrow@Aurora.com]
Sent: 06 September 2006 23:01
To: VRF
Subject: [vrf] GPIB question...
Greetings All,
Â
A question about control over the GPIB. We have A PC controlling a test system; it’s running some kind of scripting language. We would like to hook up another computer, let’s say my laptop, to control the same instruments. Is there any way to do this without disconnecting the first PC from the GPIB? I stopped the program and exited the application on the first PC, but somehow it doesn’t seem to relinquish control over the bus. I’ve gotten around this in the past with a GPIB switch, but I was wondering if there was some other way.
Â
Thanks in advance,
Doug
Â
Douglas B. Rudrow
Systems Development Lab Technologist
Aurora Networks
2803 Mission College Blvd.
Santa Clara, California, 95054
U.S.A.
(408) 235-7000 Main
(408) 235 7084 Direct
HYPERLINK "mailto:rvilla@aurora.com"drudrow@aurora.com
Â
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Â
Only one device in a system can be system controller. The SYSTEM controller is never passed. ACTIVE control can be passed. This grants permission for the active controller to assert the ATN line. However, the system controller retains control of the interface clear hardware line, and I believe also the REN line (remote). Asserting the ifc line will clear bus traffic, but will also return active control to the system controller.
Â
If there are two active controllers you find that one is constantly driving the ATN low and the other attempting to drive it high. This causes current flow that can potentially damage cards, and will definitely cause unreliable bus traffic. Whether it works will depend on a lot of factors like relative cable length and the number of devices loading the bus.Â
Â
Short answer, don't do it.
Â
However, back in the day we used to simply turn off the controller we weren't using. A GPIB system will work if at least 1/2 of the devices connected are powered up. We also used to violate the total length and the having a load every meter rules as well. The 16 max devices was a hard rule though and attempts to exceed that would cause the bus to fail.
Â
Jay Nemeth-JohannesÂ
Smart Sensor SystemsÂ
720 SW 14th Street
Loveland, Colorado 80537
(970) 663-0006Â (Office)
(970) 290-9797 (Cell)
HYPERLINK "http://www.smartsensorsystems.com/"www.SmartSensorSystems.com
Â
 _____ Â
From: Street, Andy M [mailto:andy.street@tycoelectronics.com]
Sent: Thursday, September 07, 2006 6:28 AM
To: VRF
Subject: RE: [vrf] GPIB question...
Hi Doug et al,
Â
Warren is correct - only one person can be the boss at any given time. In others words, GPIB only allows for one system controller at a given instant. I am not too sure what your ultimate goal is with all of this, but it may be worthwhile considering GPIB via LAN. Either use a dedicated GPIB/LAN box such as an E5810 or use a PC equipped with a GPIB interface and configure as a LAN server (this could be the existing PC). Basically your laptop (hooked to the PC with the GPIB resource via LAN) and the PC itself use the same GPIB resource. Issue is that you will have to manage any contention i.e. you want to control instruments whilst the script is doing stuff with them. GPIB-LAN server has been available in IO libraries for a long time.Â
Â
Andy
 _____ Â
From: Pickles, Warren [mailto:Warren.Pickles@tycoelectronics.com]
Sent: Thursday, September 07, 2006 3:17 AM
To: VRF
Subject: RE: [vrf] GPIB question...
Doug,
Â
I've never done anything like that, but I think this is how it's done: Only one device on the GPIB can be the controller; usually this is a PC sending commands to instruments. To do what you want to do, you have to pass control between the two PCs. You need to know the GPIB addresses of the two PCs (they must be different), and then you execute a pass_control command from the controller PC to the other PC. From VEE you do this with I/O, Advanced I/O, Interface Operations, then configure a transaction appropriately.Â
Â
Regards,
Warren
 _____ Â
From: Douglas Rudrow [mailto:drudrow@Aurora.com]
Sent: 06 September 2006 23:01
To: VRF
Subject: [vrf] GPIB question...
Greetings All,
Â
A question about control over the GPIB. We have A PC controlling a test system; it’s running some kind of scripting language. We would like to hook up another computer, let’s say my laptop, to control the same instruments. Is there any way to do this without disconnecting the first PC from the GPIB? I stopped the program and exited the application on the first PC, but somehow it doesn’t seem to relinquish control over the bus. I’ve gotten around this in the past with a GPIB switch, but I was wondering if there was some other way.
Â
Thanks in advance,
Doug
Â
Douglas B. Rudrow
Systems Development Lab Technologist
Aurora Networks
2803 Mission College Blvd.
Santa Clara, California, 95054
U.S.A.
(408) 235-7000 Main
(408) 235 7084 Direct
HYPERLINK "mailto:rvilla@aurora.com"drudrow@aurora.com
Â
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<b><span style='font-weight:bold'>Sent:</span></b> Thursday, September 07, 200612:17 AM
<b><span style='font-weight:bold'>To:</span></b> VRF
<b><span style='font-weight:bold'>Subject:</span></b> RE: [vrf] GPIBquestion...</span></font><o:p></o:p></p></div><p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:12.0pt'><o:p> </o:p></span></font></p><p class=MsoNormal><font size=2 color=blue face=Arial><span style='font-size:10.0pt;font-family:Arial;color:blue'>Doug,</span></font><o:p></o:p></p><p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:12.0pt'> <o:p></o:p></span></font></p><p class=MsoNormal><font size=2 color=blue face=Arial><span style='font-size:10.0pt;font-family:Arial;color:blue'>I've never done anything like that, but Ithink this is how it's done: Only one device on the GPIB can be thecontroller; usually this is a PC sending commands to instruments. To dowhat you want to do, you have to pass control between the two PCs. You needto know the GPIB addresses of the two PCs (they must be different), and thenyou execute a pass_control command from the controller PC to the otherPC. From VEE you do this with I/O, Advanced I/O, Interface Operations,then configure a transaction appropriately. </span></font><o:p></o:p></p><p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:12.0pt'> <o:p></o:p></span></font></p><p class=MsoNormal><font size=2 color=blue face=Arial><span style='font-size:10.0pt;font-family:Arial;color:blue'>Regards,</span></font><o:p></o:p></p><p class=MsoNormal><st1:City w:st="on"><st1:place w:st="on"><font size=2 color=blue face=Arial><span style='font-size:10.0pt;font-family:Arial; color:blue'>Warren</span></font></st1:place></st1:City><o:p></o:p></p><blockquote style='margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt'><p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:12.0pt'><o:p> </o:p></span></font></p><div class=MsoNormal align=center style='text-align:center'><font size=3face="Times New Roman"><span style='font-size:12.0pt'><hr size=2 width="100%" align=center tabIndex=-1></span></font></div><p class=MsoNormal style='margin-bottom:12.0pt'><b><font size=2 face=Tahoma><spanstyle='font-size:10.0pt;font-family:Tahoma;font-weight:bold'>From:</span></font></b><fontsize=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> DouglasRudrow [mailto:drudrow@Aurora.com]
<b><span style='font-weight:bold'>Sent:</span></b> 06 September 2006 23:01
<b><span style='font-weight:bold'>To:</span></b> VRF
<b><span style='font-weight:bold'>Subject:</span></b> [vrf] GPIB question...</span></font><o:p></o:p></p><p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>Greetings All,</span></font><o:p></o:p></p><p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:12.0pt'> <o:p></o:p></span></font></p><p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>A question about control over the GPIB. We have A PCcontrolling a test system; it’s running some kind of scripting language.We would like to hook up another computer, let’s say my laptop, tocontrol the same instruments. Is there any way to do this without disconnectingthe first PC from the GPIB? I stopped the program and exited the application onthe first PC, but somehow it doesn’t seem to relinquish control over thebus. I’ve gotten around this in the past with a GPIB switch, but I waswondering if there was some other way.</span></font><o:p></o:p></p><p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:12.0pt'> <o:p></o:p></span></font></p><p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>Thanks in advance,</span></font><o:p></o:p></p><p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>Doug</span></font><o:p></o:p></p><p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:12.0pt'> <o:p></o:p></span></font></p><p class=MsoNormal><em><b><i><font size=2 color="#800040" face="Times New Roman"><spanstyle='font-size:10.0pt;color:#800040;font-weight:bold'>Douglas B. Rudrow</span></font></i></b></em><o:p></o:p></p><p class=MsoNormal><strong><b><i><font size=2 color=navy face="Times New Roman"><spanstyle='font-size:10.0pt;color:navy;font-style:italic'>Systems Development LabTechnologist</span></font></i></b></strong><o:p></o:p></p><p class=MsoNormal><ST1:CITY><ST1:PLACE><st1:City w:st="on"><st1:place w:st="on"><strong><b><font size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial; color:navy'>Aurora</span></font></b></strong></st1:place></st1:City></ST1:PLACE></ST1:CITY><strong><b><fontsize=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;color:navy'> Networks</span></font></b></strong><o:p></o:p></p><p class=MsoNormal><ST1:STREET><ST1:ADDRESS><st1:Street w:st="on"><st1:address w:st="on"><strong><b><font size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;color:navy'>2803 Mission College Blvd.</span></font></b></strong></st1:address></st1:Street></ST1:ADDRESS></ST1:STREET><o:p></o:p></p><p class=MsoNormal><strong><b><font size=2 color=navy face=Arial><span lang=ESstyle='font-size:10.0pt;font-family:Arial;color:navy'>Santa Clara, California,95054</span></font></b></strong><o:p></o:p></p><p class=MsoNormal><strong><b><font size=2 color=navy face=Arial><span lang=ESstyle='font-size:10.0pt;font-family:Arial;color:navy'>U.S.A.</span></font></b></strong><o:p></o:p></p><p class=MsoNormal><strong><b><font size=2 color="#800040" face=Arial><spanstyle='font-size:10.0pt;font-family:Arial;color:#800040'>(408) 235-7000 <st1:placew:st="on"><ST1:PLACE>Main</st1:place></span></font></b></strong></ST1:PLACE><o:p></o:p></p><p class=MsoNormal><strong><b><font size=2 color="#800040" face=Arial><spanstyle='font-size:10.0pt;font-family:Arial;color:#800040'>(408) 235 7084 Direct</span></font></b></strong><o:p></o:p></p><p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:12.0pt'><a href="mailto:rvilla@aurora.com"><strong><b><font size=2color="#800040" face=Arial><span style='font-size:10.0pt;font-family:Arial;color:#800040;text-decoration:none'>drudrow@aurora.com</span></font></b></strong></a><o:p></o:p></span></font></p><p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:12.0pt'> <o:p></o:p></span></font></p><p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:12.0pt'>
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