Vertigo @ MFF @vertigo@mastodon.social

Hey fediverse bot authors, this is for you.

Instead of having a bot that blindly follows someone, then having a pinned toot or description that reads, "DM me "unfollow" if you don't want me to follow you any more", how about you do something sensible like looking at a user's profile and discovering whether or not they have #nobot in it first?

Because if you write bots that don't respect #nobot, you're no better than a spammer.

Don't @-me.

I am not looking forward to reworking the guts of the SIA's receiver logic. Bleh.

This runs counter to how CRC is typically calculated, where the trailing 0 bytes are considered, but have no impact on the CRC calculation. In ModBus, they **do** have impact.

Excuse me while I clean up my hair from the floor.

Ho ho ho -- more news in this area. It looks like the inverter *is* implementing the correct CRC algorithm, and that my ModBus spec document has the wrong algorithm.

It seems that ModBus calculates its CRC over all message bytes **except** the CRC bytes (which would be set to zero before transmission). **Then** it stuffs the CRC bytes with the calculated value, and then sends off the data.

Yet, the software that they bundled with the unit works flawlessly.

Time to invest in a logic analyzer and get to reversing this protocol.

OH, I should point out: the reason I engaged in this nonsense in the first place is because exactly ZERO (see also 0; the empty set, and the set of all empty sets) Python ModBus modules work with our unit, so I thought, OK, I'll go straight to the hardware myself then. And sho-nuff, nothing fucking worked.

it's different.

SO, not only is this vendor using customized function codes, they're also possibly using a bad CRC algorithm as well.

Why would someone do this? Who the fuck thought this was a good idea?

ModBus is a *standard* for a reason, mother fuckers. Use it, or stop calling your shit ModBus compliant.

Why.

Not a question, but a statement of WHAT THE ACTUAL FUCKERY IS THIS level of frustration, except I'm utterly defeated.

At work: inverter unit claims to use ModBus protocol. I write a program that calculates a frame's CRC-16 as documented by the vendor's own algorithm.

I try a sample frame from Wikipedia (which happens to also include a correct CRC, or so they claim), and ....

Them eyes!

I should clarify -- it is formally verified insofar as BMC checks are concerned. I still need to make it pass induction too. This is the __//HARD//__ part. >:/

Made excellent progress on my #Kestrel3 SIA core's receiver logic last night. It is formally verified to be correct, so I'm hoping I can find the time tonight to wrap the SIA core all together and implement local loopback logic. This will probably take all evening.

Then, hoping tomorrow evening, I can implement the Verilator code to drive the SIA core from the processor's point of view and verify in simulation that the core as a whole works.

Then, the SIA will be done done.

TIL: Effable does not mean fuckable. It means, literally, able to be described in words.

The frequency with which she's falling ill has me terribly worried. I strongly urged her to see her doctor and to make sure to tell them that this is the 3rd time this year with consistent symptoms.

I don't know what else can be done at this point.

There is nothing worse than having a poor day of productivity at work, then coming home to your significant other sick, with a terrible chest cough, for the third time this year. Poor appetite, unable to speak, total head congestion. The only difference this time versus the last two is she has no fever.

It's absolutely heart-wrenching. I want to help so much, but I just can't.