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SCPI Reading and Saving SNP Data with N5235A

Question asked by maxplus on Dec 11, 2017
Latest reply on Dec 26, 2017 by tsilchia

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I was wondering if anyone has run into this issue. I have been using the commands "CALCulate<cnum>:DATA:SNP:PORTs? for reading SNP and

"CALCulate<cnum>:DATA:SNP:PORTs:SAVE <"x,y,z">,<filename>" to remotely save s2p data to a specified file path.

On the first command, the Command Expert is prompting for x,y,z input but there is no field available to enter.

On the second command for saving SNP, Command Expert (v1.7) throws up error as: SCPI Error, 103 CALC measurement selection to none.

Listed below is the model and firmware information for the affected analyzer. Thanks for your time!

PNA-L N5235A

A.9.90.19

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maxplus Dec 11, 2017 9:27 AM
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This is the command I use for saving SNP data and as a result an error message is thrown up

:CALCulate:DATA:SNP:PORTs:SAVE "1,2","test.s2p"
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DavidC Dec 11, 2017 10:08 AM
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Not exactly clear on how command expert works, so kinda can't help on the 1st one , other than you need to give the quoted port numbers like you do in you save example after the ports?

On your 2nd Issue, which will also be a issue on the 1st one (once it resolved), is you need to select a trace for the channel to collect the S2P so prior to requesting data you need to send command,
'calc:par:sel "<Mname>"'
and the mname is the name of the measurement you want to query. If you did not programmatically create the measurement and don't know the manme you can determine the mname from
"calc:par:Cat?"
If the pna generated it , it should take the form "CH1_S11" or so .
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maxplus Dec 11, 2017 2:12 PM
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Hello
Thank you for the assistance. I'll try your recommendation very soon.

Do you have an example file that you can share? Is the process that you firstly select the trace followed by reading and lastly saving.

You are right about specifying the ports during reading but Connection Experts throws up a message when specifying.

Regarding Connection Expert, it is a Keysight IO utility program that allows you to communicate, send and receive SCPI based commands via GLOBAL or LAN.
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- DavidC @ maxplus on Dec 11, 2017 6:30 PM
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  Yea i understand what it dose , it a little GUI heavier of a interface which is aware of the scpi commands of the instrument you trying to talk to. Believe it also has a component of it helps you find the command you looking for and then generates the code for the programming language you are using (Which i assume is what you looking for). Usually I just stick with the interactive IO if I just need to quickly test commands in a console style interface but then you need the Help file and examples readily available. Speaking of which
  PNA Help
  Here is a discussion and example that covers selecting of measurements, and creating measurements
  Referring to Traces, Measurements, Channels, and Windows Using SCPI
  Channels, Windows, and Measurements using SCPI
  
  If you not doing any trace manipulation beside formatting and calibration (Ie No Data/mem, port extension, offsets) You may be best in creating a new measurement , feeding it to a window and selecting it then getting the sparmeter the read back should be the same no matter the parameter of the trace.
  
  calc:par:Def "Sparam", s21
  DISP:WIND:TRAC23:FEED "Sparam" \\ i have trace 23 to try to avoid any collisions with preexisting traces
  Calc:par:Sel "Sparam"
  CALCulate:DATA:SNP:PORTs:SAVE "1,2","test.s2p"
  
  Otherwise you can send a query
  "Calc:par:Cat:Ext?"
  which should return a string comma separated list for each trace consisting of {<mname>,<parameter>} so for example if you have 3 trace s11,s22, s21 a return could look like "CH1_S11_1,S11,CH1_S11_2,S21,CH1_S11_3,S22"
  so the mnames are "CH1_S11_1","CH1_S11_2","CH1_S11_3" and the parameters dictate what the measurement is actually measuring.
  Now you can either human read the measurements mname and hard coding your further code, or programmatically parse the string and selecting the mname of the parameter of the trace you want.
  So after getting the mname of the trace you interested in you send
  
  Calc:par:Sel "CH1_s11_1"
  CALCulate:DATA:SNP:PORTs:SAVE "1,2","test.s2p"
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maxplus Dec 11, 2017 2:13 PM
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I refer global to GPIB.
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hognala Dec 11, 2017 2:36 PM
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In Command Expert, it puts x, y, and z together, so you need to specify them as comma separated values, like in this screenshot:
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- maxplus @ hognala on Dec 11, 2017 3:16 PM
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  Hello
  Thank you.
  I don't see the field to specify the xyz criteria in Connection Expert (2017 version) when trying to read the snp (saving ok). How did you enable thst field please?
  
  Does saving the snp command automatically reads thw SNP data or is that doe separately?
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  - maxplus @ maxplus on Dec 11, 2017 3:19 PM
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    I'm using Command Expert (v1.7).
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hognala Dec 12, 2017 6:55 AM
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What Firmware Version is the Command Set using? I grabbed the latest, which is A.10.49.10. You can get the latest Command Set for this instrument by going to File --> Manage Command Sets --> Then installing the latest PNA Command Set. Once you have it installed, you can go back to the Connect Step for your sequence and change the Command Set to the latest version. At that point you should see the xyz field.
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- maxplus @ hognala on Dec 12, 2017 9:38 AM
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  Very strange that I do not see the xyz option with the latest command set for PNA (A.10.49.10).
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  - hognala @ maxplus on Dec 12, 2017 9:48 AM
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    Screenshot? Or maybe attach the .iseq?
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maxplus Dec 13, 2017 7:51 AM
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Hello,

Please find attached a screen whilst trying to read the SNP. As you can see that an error message pops up expecting to input xyz but none available.
Also, find a screen whilst saving - no problem in specifying xyz.
I have also attached the sequence file that selects the trace (but an error message pops up) and reading/saving s2p.

(Connect "N5235A", "GPIB0::16::INSTR", "PNA Network Analyzers / A.10.20.03")
:HCOPy:FILE "D:\Test\test4.JPG"
:CALCulate:PARameter:CATalog?
:CALCulate:PARameter:CATalog:EXTended?
:CALCulate:PARameter:MNUMber:SELect 1
:CALCulate:PARameter:SELect "CH1_S11_1,S21,CH1_S21_2,S21,CH1_S12_3,S12,CH1_S22_4,S22"
*CLS
:CALCulate:DATA:SNP?
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- DavidC @ maxplus on Dec 13, 2017 10:15 AM
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  2 quick things.
  You only need to use one catalog command, either works though if you using none s parameter receivers
  calc:par:cat:ext?
  is easier to parse.
  The other is the calc:par:sel looks like you copied the whole measurement catalog, you want to use only one of the measurement names which is "CH1_S11_1", "CH1_S21_2" , "CH1_S12_3", "CH1_S22_4,"
  so it should be
  :CALCulate:PARameter:SELect "CH1_S11_1"
  The SNP Data request
  :CALCulate:DATA:SNP? '1,2'
  will return all the s parameters for those ports, S11,S21,S12,S22
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  - DavidC @ DavidC on Dec 14, 2017 8:44 AM
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    Another note you could just use this
    :CALCulate:PARameter:MNUMber:SELect 1
    the number is the TR# on the pna display, so if you want to select the s22 measurement it be
    :CALCulate:PARameter:MNUMber:SELect 4
    and forget about the
    :CALCulate:PARameter:CATalog?
    :CALCulate:PARameter:CATalog:EXTended?
    :CALCulate:PARameter:SELect "CH1_S11_1,S21,CH1_S21_2,S21,CH1_S12_3,S12,CH1_S22_4,S22"
    commands these are only required if you using older pnas that don't have the mnumber:select commands, or automating trace creation and data collection.
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hognala Dec 13, 2017 8:04 AM
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Thanks for the screenshot, that helped a lot. Notice the area I have highlighted in the screenshot, there are scrollbars. If you scroll down you will see the x,y,z input field. You must be working on a really little screen? Maximizing Command Expert will help you see all of the content better
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maxplus Dec 18, 2017 1:35 PM
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Dear DavidC and Hognala,

Thank you for all the assistance - very much appreciated. As a result, the script is working which captures the .s2p file. I have a query regarding the OPC command. Instead of using time delay, I want to make use of the OPC or Wait command to check whether a particular action is completed before proceeding to perform another action. I used the OPC previously in recording power meter readings before sweeping to a new signal generator level but SCPI Timeout error msg occurred.

The reason being for asking is that in the next phase of the script, I want to sweep the power levels of the network analyser after capturing .s2p (for swept frequencies).

1. How do I use the OPC command please?
2. What are the commands for recording AM/AM and AM/PM for swept power levels?

Thank you.
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tsilchia Dec 26, 2017 12:17 PM
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Hello,

Item 1 - *OPC? related.
If you are 'timing out" with the use of *OPC? then the most probable cause is that the time to complete the predicating command functionality is longer than the default timeout setting which is typically 5s. Within Command Expert you can alter a devices default timeout via Transport - Default Timeout selections. The entry is in milliseconds.

Item 2 - AM / AM and AM / PM stimulus query.
Not sure if I am addressing your inquiry based on the question. My assumption is that you are performing swept CW power sweeps and would like to query what the individual power levels are? If this is the case then use the SENS:X? query to return the stimulus, i.e. the power values. For example a 1GHz CW power sweep from -10dBm to 0dBm, with 11 points will return the following data to the SENS:X? query: -10, -9, -8, -7, ...,-2, -1, 0 (all in dBm).

Sincerely,
tsilchia.
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SCPI Reading and Saving SNP Data with N5235A

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