Telnet.write() is too fast for some hardware targets

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Piotr Król

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Jul 23, 2017, 6:05:19 PM7/23/17
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Hi all,
I'm trying to utilize Robot Framework to automate PXE boot testing.
I'm using RS232-USB adapter and ser2net set to 115200.

I spent couple hours trying to figure out what is wrong with my test:

```
Test1
Write Bare help\n
Read Until iPXE>
```

and it looks like the problem is that `Telnet.write()` function is to
fast that my hardware configuration cannot handle that. When I tried:

```
Test1
Write Bare h
Write Bare e
Write Bare l
Write Bare p
Write Bare \n
Read Until iPXE>
```

In output buffer I have just `h`, but adding `Sleep 0.1` in between
writes give me correct result.

I wonder if anyone faced similar issue. Most probably there is no
interest in having API for slow typing in Telnet. Obviously writing
anything with above manner would not be effective. Keeping fork of
robotframwork with modified write function also doesn't seem to be
good long term solution.

What would be recommended way of applying this workaround ?

Best Regards,
- --
Piotr Król
Embedded Systems Consultant
https://3mdeb.com | @3mdeb_com
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Hélio Guilherme

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Jul 23, 2017, 7:17:49 PM7/23/17
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Must you connect at 115200 BAUD? If not you could slow down the communication, say at 9600 BAUD.
I don't know the libraries, but if they allow to change the speed after doing your text input, then you could go back to normal speed.

This is just my 2 cents (I never used telnet library).

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Pekka Klärck

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Jul 29, 2017, 6:06:35 AM7/29/17
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Hello,

If you can find a way how the Telnet library could be enhanced to slow
down writing that could be considered. If you have more special needs,
it might be easiest for you to implement a custom library instead.
Robot's library uses Python's `telnetlib` internally and you could
easily it from your own library too.

Cheers,
.peke
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Michal Smrž

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Jul 31, 2017, 5:23:31 AM7/31/17
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I agrree with custom library, but if you want to stick with robot syntax for portability, this should do the trick.

*** Settings ***
Library    String

*** Keywords ***
Slownet
    [Arguments]    ${data}    ${sleep_after_send}=${0.1}
    [Documentation]    One letter at time
    @{splitted}=    Split String To Characters    ${data}
    : FOR    ${char}    IN    @{splitted}
    \    Log    Sending ${char}
    \    Sleep    ${sleep_after_send}

*** Test Cases ***
Test
    Slownet     Send this slowly
   

 
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