Continued work on Protek D620 Serial

To begin searching for any characters that get a response, the header can simply be 02 and the tail can be 0D.   We will scan the entire uppercase alphabet by starting at $41 and continuing to $5a.   Without a parameter byte, the response will be empty but a response will still come back, which is all we care about.   The commands that give a response are:

D, F, H, L, M, Q, R, S

2 44 3F D   –   d 0 0 0         0 . 0 3 6 m V d c

2 46 3F D   –   f 0 0

2 48 3F D   –   h 1

Most of these commands are already documented, but we had not previously known that the H (Hold) command would return the state of Hold – interesting…   At any rate, there’s a ton of other stuff still waiting inside the device for us to figure out the right commands to use it.   By deleting the header and scanning from 00 on, we can get some clues on what bytes are interpreted as special (00, 01, 02) and what are interpreted as kinda-special, but only because they are not yet ascii (Everything up to 21).   More specifically, deleting the header bytes and making the tail bytes 48 3F 0D (the tail of the H? command) we can see that 00 and 01 are interpreted differently, but everything from 02 to 21 is interpreted the same as 02 – start of command.   Additionally, anything above $21 is no longer interpreted as a command.

0 48 3F D   –   f 0 0

1 48 3F D   –   f 0 0

2 48 3F D   –   h 0

3 48 3F D   –   h 0

4 48 3F D   –   h 0     …

20 48 3F D   – h 0

21 48 3F D   – h 0

The first two responses are unique, for $00 and $01.   Then, we get the expected $02 response all the way until $21.   In binary, that’s 001x xx10.   It looks like anything within the x’s is a command.   Starting at 0010 and continuing to (but not including) 0010 0010.   This gives us an idea of how the command interpreter works, and can be useful for classifying unknown functions.

Ok folks – that’s plenty for now.   We will begin compiling the function lists, and you all be sure to let us know if you come across anything great. To assist you in that, we present the exe and source for the query tool.   enjoy!

The Protek D620 Automated Query Tool with Source