ARDUINO UNO as a USB to GPIB controller - version 6.1

TEK2232 loves Arduino

Fluke PM2534 loves Arduino

Disclaimer:
This program is provided as is. It is a hobby work.
It doesn't work correctly. It has not been tested. It can damage your Arduino and the device you connect it to.
Can have unexpected behaviors, can get stuck at any moment, can read and write data to/from the device in ways you might not expect. It can send wrong or erratic commands to the device. Can display data that differ from the actual data the device sent out. Can address GPIB devices differently from what you might expect.
I have not conducted any speed test; the maximum speed supported is simply unknown.
Is does not follow any official standard. Only a minimum set of the functions included in IEEE-488 is barely emulated.
Hardware limitations: the lack of a GPIB line driver has two major implications: first: your Arduino is directly connected to the device GPIB port without any form of electrical protection of buffering - this can potentially damage your Arduino and/or your device; second: what can happen if you connect more than one GPIB device to the BUS is unpredictable both from an hardware and software point of view. I only experimented with a single GPIB device connected to the BUS.

Arduino USB to GPIB firmware by E. Girlando is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
Permissions beyond the scope of this license may be available at mailto:emanuele_girlando@yahoo.com.

After nights spent coding, this post is about version 6.1 of my USB to GPIB controller software for ARDUINO UNO.
Version 6.1 ??!! Yes, that's it! This is actually version 2 of my software, but because some third party software - actually KE5FX GPIB toolkit -  relies on the content of the output string as issued by the "++ver" command to work properly, I had to force the string "version 6." as part of the" ++ ver" command output. So .. this version has become version 6.1. 

Version 1.0 has been presented in this related post.
Version 1.0 was very crude. Most a beta version to verify the feasibility of this project.
I want to thank you very much all of you that provided me feedbacks.

Arduino UNO as a USB to GPIB adapter / controller

NOTE:
This version is OBSOLETE!! Please go to this post for the 6.1 release software and documentation.
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Version 1 of this project is aimed to provide a cheap and quick GPIB solution to those that need to gain control over a single instrument and interact with it (e.g. to calibrate instruments that can be calibrated by GPIB only -- 6632A Power Supply being a good example).

I supposed that cheap adapters were available on the market to interface GPIB instruments with a PC. I was wrong. The only feasible solution is to go with a Prologix USB to GPIB converter, still it would have cost me some tens of bucks.
Other solutions required buying or building hardware.

On the other end I had an Arduino UNO floating around on my bench waiting for a problem to solve other than blinking leds or writing "hello world" on an LCD..

So I decided to face the challenge of writing down a c++ program and have the Arduino play the adapter role I was looking for.
To make a long story short.. (I supposed that GPIB was simple at least as much RS-232 is, .. and it is not! I was wrong again!) after reading a lot of IEEE-488 documentation and giving a try to a similar program I found over the internet, I got a decent implementation of a GPIB controller out of my Arduino UNO. This post is dedicated to describe the project.