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Re: GPIB workflow
On 2025-03-22 10:11 PM, Radu Bogdan Dicher via groups.io wrote:
If I understand correctly, you're saying that the # GPIB connection mayGPIB doesn't have the concept of a "connection". Each device sets its own address, sometimes via DIP switches, sometimes, via front panel commands, etc., but that instrument "knows" its own address. It's up to the user to ensure there are no collisions. There are 31 available addresses - often set by 5 DIP switches. The 32nd address is reserved as described below. The whole concept is quite different from either USB or Ethernet addressing. To start a data transfer (which may be a command, or some sort of data), the Controller (usually a PC adapter of some sort these days; could be an internal board with special drivers, or external like my KISS-488) issues a command to one address (maybe even itself) to become the Talker, and to one or more devices (instruments) to become a Listener. The talker then proceeds to send bytes, ending with a specified termination condition. The Controller usually then turns the bus around, addressing e.g. the instrument to become Talker, and e.g. itself as Listener, and data flows the other way. at the end, it issues Untalk and Unlisten commands (that 32nd address). I include a fairly detailed discussion of GPIB concepts in the beginning of the manual for my KISS-488, which you can download freely at Steve Hendrix |
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Re: GPIB workflow
On Sun, Mar 23, 2025 at 03:11 AM, Radu Bogdan Dicher wrote:
The address is selected in the scope (like most other instruments) and you don't have to reboot if you change it. If you have National Instruments GPIB hardware you can try and play with this /H?kan |
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Re: GPIB workflow
Thank you, Harvey.
If I understand correctly, you're saying that the # GPIB connection may "port" another, "hot swapped" instrument to the same # GPIB? I got impatient after posting this and thought I'd play with it a little more and I connected the GPIB interface to the TDS754D then booted it and it just landed on #4 GPIB. Not sure why on #4 (whether it had to be "elevated" at #4 and why there's three below that having nothing connected). Generally speaking, I'm seeing different instruments landing on a pretty wild "#" GPIB port. I'm always doing a "list" to inquire which GPIBs have something attached. Radu. On Sat, Mar 22, 2025 at 6:54?PM Harvey White via groups.io <madyn= [email protected]> wrote: The 488 bus is an addressed bus, which means recognizing an address on a |
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Re: GPIB workflow
The 488 bus is an addressed bus, which means recognizing an address on a bus and having something respond (think I2C for an example).
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So when you hot swap instruments, assuming that you don't glitch something, then an existing address doesn't respond, and a new address doesn't yet get recognized. The controller (and I think it doesn't , unlike USB) start a new connect sequence.? You'd have to program it. That means, to autoconnect, you'd need to be polling the interfaces (all of them), and when one doesn't respond, you need to forget it.? You then need to scan for a new device.? (and 488 has, IIRC, none of that), although the controller? by polling each device. So somewhat different there, and not like USB. Harvey On 3/22/2025 7:47 PM, Radu Bogdan Dicher via groups.io wrote:
Hi all, |
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Decomposing Cam Switch Drum
I recently acquired a PG502 from Tek surplus (aka Country Store) and found several setting to be intermittent. Expecting that a good cleaning would be in order, I was astonished to find that cam switch drum appears to be decomposing. It looks dull, powdery and parched like mud flats after a dessert gully washer!
In fact, there was a lot of fine debris on the contact board. Cleaning the board and the contacts made no difference because the cam lobes are deteriorating. I have not touched the cam drum with any cleaner or other chemicals. This unit was used in the production test area; perhaps its entire life. It was last cal’d June 2022. Perhaps it is the result of 45 years of continuous up time in a rack. I have never seen a cam drum look like this. Has anyone seen such a thing? (See photo gallery for “Decomposing Cam Switch Drum.”) |
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GPIB workflow
Hi all,
As I'm exploring GPIB in my environment on multiple instruments, a newbee question - is GPIB essentially hot swappable? Differently put, can I typically just hook it up to an instrument that's running and expect it to smoothly connect? Or is it typically better to connect GPIB while the instrument is off, then turn it on, so it'd scan its "peripherals" during the booting sequence and this would guarantee it's connecting with no issues? I assume there's a rule of thumb, instead of a situation where maybe all instruments may be different and it's hard to tell what's the best approach. I've connected it plenty before, but 95% of the time it's been hooked up to one instrument and so "hot swapping" wasn't a consideration. This is for a TDS754D, reason I'm posting on this board, but I'm looking for some input applicable to any instrument/brand. Thank you, Radu. |
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Re: Adapter PCBs for 148-003x-00 relay replacement
Hello everyone,
its been a while since my last post. There were a lot of things which kept me from posting an update. Nevertheless, I finally managed to do some measurements of my relay replacements. The VNA at work was blocked all the time. Therefore, I had to find a different way to measure the relays. In the Album there are now the measurement result of almost all possible combinations you can have in a DPDT relay. /g/TekScopes/album?id=299851 All in all the replacements perform quite a bit worse than the originals. This is not surprising as the original relays are close to perfect in terms of HF coupling (tiny cross sections with relatively large gaps between adjacent parts). The PCB in contrast provides 'long' traces in parallel. As the VNA was not available I had to measure the relays with a automated setup composed of my 60MHz function generator as signal source and my digital oscilloscope as measurement device. Due to the noise floor of the oscilloscope and the low output level of the funtion generator dynamics of the measurement was not crazy high. To get an impression how much coupling would be possible at the given distances between pins, I always measured one complete trace without any DUT at all (the traces called 'Fixture'). Nevertheless, the measurements always show that the replacement performs not as good as the original relay, but I think this is the price you will have to pay to get a relaibly switching relay. Regarding leckage current I will try to perform a few measurements to see if the required 0.2nA is achivable or not. I hope the next update will not be delayed as much as this one. Right now I have 4 unpopulated panels left over (each with 36x 148-0034-00 and 30x 148-0035-00 relays). Plus some additional ones of the first panel which were already populated with SMT components. If you are interested, send me a message off list with your needs and we can discuss how I can help you. Best regards, Wolfgang |
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Re: Succesfully upgraded TDS620 to TDS640.
Wamor,
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If you see the service manual, there is an annotation: "Version ID resistor placement: place U4 & R12-R17 only on boards that have exceeded the ID number 11110XXX. In this case, the version number is decoded via pins 2,3,4 of U4. R7,R9,R11 are not placed & pins 5-9 of U3 are wired high" Regarding TDS640 ID, I sent the ID from TDS640A to you. I do not have them for TDS640, but I can see that TDS520,TDS540, and your TDS620 have the same IDs. Regarding AUX and Ch, Aux input has a simplified schematics than Channel on two channel boards. Maybe new firmware will fix the wrong names. And maybe some additional calibrations will be needed after the wrong hardware error will be fixed. Regarding NVRAM backup, See tektool program here: !-(firmware-flash-tools-for-old-tds-series)/ This one do not work on my PCII/IIA card, which i bought for Field Adjustment, but works on Prologix, as i know. WBR, Peter сб, 22 мар. 2025?г. в 18:27, wamor2006 via groups.io <tektronix= [email protected]>: Hi Peter, |
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Looking for TDS640 firmware
Hello all,
I have upgraded my TDS620 scope to display 4 (=>TDS640) by reconfiguring the acquisition board resistors. The scope is reporting to be a TDS640 and the channels are visible and working. Only in the log-file the scope is reporting that the number of channels is incorrect every time at startup. I’ve learned on this forum that the firmware for the TDS640 differs from the TDS620 firmware but that version-numbers is the same. Could someone maybe supply me with the TDS640 firmware? Regards, Wamor |
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Re: Succesfully upgraded TDS620 to TDS640.
Hi Peter,
No problem, your are not encouraging me. This only gives me more energy to sort this out. Could you give me the ID to set with U3 for the TDS640 which you have in your table? And maybe also for the TDS620? I saw some pictures in the internet of the TDS640 CPU board and there the resistors connected to U3 are the same as on my TDS620 CPU board? When I look at the pictures I also see that the version numbers of the software are the same Another reason that H?kan is right. What I also see on my scope that the extra channels are identified on the screen as AUX1 and AUX2 and not CH3 and CH4 what I was expecting. Yes, your right. I need to find the firmware for the TDS640 then. I will post a new question on this group for that. Maybe I could remove the resistors connected to U3 and connect switches to check each configuration. Its only 7 new possibilities. I hope I don't destroy my scope when doing this. Or corrupt the NVRAM. I did the same with the acquisition board which worked really well. I am still busy creating a program in Labview to backup the NVRAM using the Prologix GPIB interface. Regards, Wamor |
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Re: 7934 Service Manual
Bob,
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Yes, thank you. I see that I concluded that it doesn't have sections 8 and 9 because I was looking at the end of the PDF, which are the Change Information pages. I do see the duplicate pages. Without a copy of the original manual (or an original manual itself) I can't tell what else might be incorrect with the online copies. Since many of the pages of the online copies are partial pages, I'd have to compare the pages in the online PDFs to an original manual. Perhaps someone out there could do that, but since the 7934 is pretty rare, I doubt that there is anyone who is paying attention to this thread who will do that. I have sent pp. 31, 6-22 and 6-23 to Mark, the OP. That will have to suffice, for now. I may upload my revised PDF that contains those three missing pages. I can scan my original that is a later revision, but that will take a lot of time due to the fold-out pages. DaveD KC0WJN On 3/22/2025 9:16 AM, mst3krules via groups.io wrote:
The copy I look at came from this link: --
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Re: Succesfully upgraded TDS620 to TDS640.
Hi Wamor,
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As far as I see the IDs on my boards, in my table, and your ID, the ID refers to something else. TDS520,TDS540,TDS620 use the same ID. Sorry to be encouraging. Maybe, H?kan is right. The only question is, where can we get the firmware from the TDS640? I'm doing similar research: how to convert TDS544A to TDS644A. The processor board is the same, the Acquisition board is different. The firmware of the TDS544A board does not see the Acquisition board from the TDS644A Regards, Peter пт, 21 мар. 2025?г. в 15:57, wamor2006 via groups.io <tektronix= [email protected]>: Hello Peter, |
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Re: 7934 Service Manual
I don't see any duplicate pages in the TekWiki copy of the 7934 manual.
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Also, the May 1986 PDF ends with section 7. My copy (Aug 1987) has sections 8 and 9. I'm a bit confused. It would be helpful if someone out there has an original, printed copy of the May 1987 (unrevised) copy of the manual. DaveD KC0WJN On 3/22/2025 7:24 AM, mst3krules via groups.io wrote:
Pages 459 - 467 --
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Re: 7934 Service Manual
Thanks.
DaveD KC0WJN On Sat, Mar 22, 2025 at 07:24 mst3krules via groups.io <mst3krules= [email protected]> wrote: Pages 459 - 467 |
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Re: 7934 Service Manual
Could you send to me the logical PDF page numbers of the pages to which you
refer? Thanks. DaveD KC0WJN On Sat, Mar 22, 2025 at 07:15 mst3krules via groups.io <mst3krules= [email protected]> wrote: I forgot to mention but I also noticed that there appears to be duplicate |
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