Hello again, fellow D620 users. Based on RL’s latest findings at the first D620 post, we’re hazarding a guess that there is more to this device than it lets on.
We were trying out his findings today, and couldn’t resist the urge to start firing random hex bytes at the device. Surprisingly enough, it responded to some of them! After playing around with format, etc, we came up with a few rules.
Some functions can be queried (H? – Hold) and also set. These functions will respond to just their main character (D, H) but will return junk – the standard header, but blank data. Sometimes, that’s all you need. Simply getting some output means that you have gotten your command past the RS232 receiving routine and into a command interpreter. So by scanning the entire ASCII table, you could determine what characters have functions that return data.
Now wouldn’t it be nice to have an automated way to do that? Enter D620Query! An automated program to send queries to the device. Anything that gets data back is logged in the bottom window. Using this tool, we can easily scan for responsive characters, and additionally scan those characters with arbitrary commands to see what happens. It’s doubtful that any of this will damage your meter (maybe erase a datalog accidentally) but regardless – you use this at your own risk.
Fig 1 – Main Window of D620Query
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