MKS Quattro

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Roberto Ferrari
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MKS Quattro

Post by Roberto Ferrari »

Hi,
I got a MKS Quattro gauge with a problem: the RS 485 doesn't answer queries.
I am willing to pull out the boards but two of them look tied by flat cables.
See attached image.
I fear to ruin the unit that still works in analog mode.
Any experience disassembling them? Web manual doesn't help about opening/repairing.
Thanks!
Roberto
IMG_20170819_163539121.jpg
Andrew Seltzman
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Re: MKS Quattro

Post by Andrew Seltzman »

The quattro gauges are typically rs-232, make sure you have the baud rate and device address correct.

I've added a matlab script that should log data from the gauge.
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Andrew Seltzman
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Roberto Ferrari
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Re: MKS Quattro

Post by Roberto Ferrari »

Thanks Andrew

As far as I understand, the model has RS485.
See plate. This brochure states it at last page.
Roberto
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Jerry Biehler
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Re: MKS Quattro

Post by Jerry Biehler »

It maybe set to a certain address and wont respond to queries without something specific. I have never messed with one so I dont know for sure.
Silviu Tamasdan
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Re: MKS Quattro

Post by Silviu Tamasdan »

I don't have experience with RS485, but have worked extensively with RS232. Serial interfaces can appear unresponsive if you don't use the correct baud/bps rate. Try querying it at different rates and see what happens.
If you have an oscilloscope see if you have any waveforms on the signal pins, that may give you an idea about the baud rate the interface expects.
There _is_ madness to my method.
Roberto Ferrari
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Re: MKS Quattro

Post by Roberto Ferrari »

Hi Silviu

I checked all the baud rates specified at the brochure and with a scope I see the train of pulses during query but no answer.

Thanks!

Roberto
John Myers
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Re: MKS Quattro

Post by John Myers »

What are you trying to connect the RS485 to?
Do you have a special USB dongle to the PC?
Roberto Ferrari
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Re: MKS Quattro

Post by Roberto Ferrari »

Hi John
I am willing to control the MKS Quattro with serial port monitor and a USB/RS232/485 adapter (bidirectional converter IC-485AI).
I need to degas the filament and modify the gas calibration.
By now no success at all.
I fear there is something wrong at the electronics and need some info in order to take out the boards without damage.
John Myers
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Re: MKS Quattro

Post by John Myers »

have you conformed that the IC-485AI is setup properly? Connecting the TX and RX pins of the IC-485AI together will create a loopback allowing you to see what you type in the console.
Roberto Ferrari
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Re: MKS Quattro

Post by Roberto Ferrari »

As a matter of fact, the IC-485AI belongs to a friend who uses it habitually and helped me in the diagnostics.
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Bob Reite
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Re: MKS Quattro

Post by Bob Reite »

From the photo, it looks like the board will slide out AWAY from the camera if you loosen the screws holding the front panel to the aluminum extrusion. The front panel and the boards will come out as one unit, but that should give you access to one side of each board.
The more reactive the materials, the more spectacular the failures.
The testing isn't over until the prototype is destroyed.
Bruce Meagher
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Re: MKS Quattro

Post by Bruce Meagher »

Roberto,

Some things you might double check before completely disassembling... Verify you didn’t mix up the +/- signals. Check your RS485 adaptor is setup as 8 data bits, no parity, and one stop bit (in half duplex mode bridge T+ to R+ and T- to R-). Check all 6 different baud rates (9600 is the default). Sending @254;FF should return @253NAK160;FF. You must send a valid command to get a response, and address 254 is the universal address all devices respond to. Also, since it’s a half duplex link the response will be on the same lines immediately after the query. Check the length on an oscilloscope to verify it’s just the query being transmitted (and not the query and the response). Sending @255;FF will not produce a response from the device as a comparison.

Bruce
Roberto Ferrari
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Re: MKS Quattro

Post by Roberto Ferrari »

Hi Bob, thanks!
I imagined that also but was willing to check with experienced people.

Hi Bruce
We checked all your suggestions to no avail.
By the way, your query is shorter that the one stated at the MKS manual: @254AD?;FF
Bruce Meagher
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Re: MKS Quattro

Post by Bruce Meagher »

I believe @254;FF is the shortest string you can send and still get a response from the device (explained near the end of the manual on debugging the comm link)
Roberto Ferrari
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Re: MKS Quattro

Post by Roberto Ferrari »

Bruce
You are right.
This weekend I will try it.
Thanks!
Roberto Ferrari
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Re: MKS Quattro

Post by Roberto Ferrari »

Bob and Bruce,

Finally there was no need to disasembly the Quattro.
It is working well now.

Testing communications at several baud rates, we got response at 19200 bauds and now we have full control of it.

Before taking control at 19200 bauds there was no answer to the short query.

Next step is to link it to LabView.
Thanks!

Roberto
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