Add Monday, the Modbus-Failure-Day

content/blog/wk4day1.md

@@ -1,7 +1,81 @@
 ---
-title: "Week 4, Monday:"
+title: "Week 4, Monday: Modbus Failure"
 date: 2024-08-19T21:55:00+02:00
-draft: true
 ---
 
 {{< image frame="true" width="17em" float="right" src="/img/headline/zascatv.png" alt="Credit: Zasca TV, Youtube" >}}
+
+Geez I had some really bad luck today. So I bought what I thought was a perfectly normal modbus
+ammeter, and I have the 32 channel variant with external current transformers. The microcontroller
+boots and seems to blink an LED every 250ms or so as it's doing its measurements. The (chinese)
+manual says it's a simple modbus device approachable via RS485 and it shows what all the 16 bit
+registers are - relatively simple stuff.
+
+Yesterday I spent the day designing the physical parts, and today I thought I'd give a go to the
+microcontroller firmware. I have written one of these before, but I seem to have ... misplaced the
+source code for it. Not to worry, I remember it was a matter of connecting the ESP32 to the modbus,
+and reading target address 1, and off to the races. Well, not today!
+
+I have eight of these units, one for each PDU. I connected one, but it was not responding on any
+target address, and not with its default serial settings of `9600,8N1`, nor with any other
+reasonable settings, nor on any other address. That's unfortunate.
+
+So I spend, what I can best describe as increasingly frustrating hours of debugging. First with
+another ESP32, then with another RS485 unit, then by hotwiring the UART out of the RS485 converter
+on the DIN module, and finally, and I say this after it turned 17:00 already, I grabbed the scope
+and started taking a look at what was going over the modbus -- and I can clearly see the
+differential (yellow is high while blue is low), but the DIN module is absolutely silent. I also
+scoped the UART 3.3V, which is pulled to 2.8V by the board, but I can't see it saying anything
+there, either.
+
+I connect the DIN module, via the hotwired GND, RX, TX, to my [[Bus
+Pirate](https://buspirate.com/)], which, by the way, is any hardware tinkerer's dream. It allows me
+to type simple commands in a terminal and talk to chips over 1-Wire, I2C, SPI, UART, and more.
+This, normally anyway, allows me to figure out how a chip works before writing a as much as one
+line of code. Neat! However, today, no dice. The DIN unit doesn't say -anything-, even when I send
+it a perfectly normal probe, described in its manual. 💩
+
+My blood pressure was rising and at around 17:30, after I think 8 hours of messing around and _not_
+finding out, I decided to give up for now. I went to Aliexpress and ordered a few alternative RS485
+dongles, including one for the PC itself, on USB, so that I can try to talk to the thing via my
+Linux computer, _Summer_. Today has been almost completely written off :(
+
+### KVM-over-IP
+
+But there was one good thing, also! In the big bag'o'packages from yesterday, there was another
+device: a NanoKVM from [[Sipeed](https://sipeed.com/nanokvm)]. This 40x40x40mm cube has a few USB
+connectors, a HDMI connector, and an RJ45 ethernet connector. It's meant to be a KVM-over-IP device,
+which can also emulate a USB CDROM, so that I can boot a specific ISO image that I uploaded to the
+little machine. It runs Linux and has an (open) SSH server. I poke around on it, create a 'pim'
+account, upload some SSH Keys, and close out password authentication. On IRC, my buddy _Habbie_
+mentions some security audit that was not overly optimistic about it - I take a look and conclude
+that it's probably safe to run in _IPng Site Local_.
+
+The microcontroller boots up and gets an IPv4 address over DHCP, which it helpfully puts on a little
+OLED display. The web interface is snappy and immediately shows _Summer_'s HDMI output at 1920x1080,
+which I find impressive. I think this will be a perfect companion for when I'm on the road and need
+an ersatz monitor. 
+
+Marina makes dinner tonight - it's my sister's recipe called _Yolein-soep_, which is a tomato soup
+made from concentrate and a white roux, with bacon bits, sjallots and rice.  After the soup, she
+serves two nice Flammkuchen, also with bacon and onions.  It hits the spot after such a frustrating
+day with RS485 and a non-working modbus. What am I doing wrong!? 
+
+I decide to not think about it for the rest of the day, and watch some TV instead. I also go to bed
+really early, at 22:00 I am already on one ear.
+
+## Pictures of the Day
+
+{{< gallery-category >}}
+  {{< gallery-photo fn="2024-08-19/IMG_0713.JPG" caption="The innards of the PDU are nicely placed in 3D printed parts." >}}
+  {{< gallery-photo fn="2024-08-19/IMG_0716.JPG" caption="The Rigol oscilloscope cannot see a problem with the differential RS485 signal." >}}
+  {{< gallery-photo fn="2024-08-19/IMG_0718.JPG" caption="I play around a little bit with the Sipeed NanoKVM" >}}
+  {{< gallery-photo fn="2024-08-19/IMG_0719.JPG" caption="The Sipeed NanoKVM shows a 1920x1080p picture from my Linux PC, Summer" >}}
+  {{< gallery-photo fn="2024-08-19/sipeed-kvm.png" caption="A screenshot of Summer's desktop as seen in a web browser, using Sipeed's NanoKVM over IP" >}}
+  {{< gallery-photo fn="2024-08-19/IMG_0720.JPG" caption="We eat Flammkuchen tonight, courtesy of Marina" >}}
+  {{< gallery-photo fn="2024-08-19/IMG_0721.JPG" caption="Leave your phone unattended, and there will be goofy pictures when you return..." >}}
+{{< /gallery-category >}}
+
+{{< gallery-modal >}}
+{{< gallery-script >}}
+

content/gallery.md

@@ -224,6 +224,20 @@ menu:
   {{< gallery-photo fn="2024-08-17/IMG_0700.JPG" caption="Quinn and I are making dinner - garlic soup and stuffed bellpepper" >}}
   {{< gallery-photo fn="2024-08-17/IMG_0702.JPG" caption="The finished product: 3 stuffed bellpeppers. Oone is buried,and  some have grated cheese (I am not a fan)" >}}
   {{< gallery-photo fn="2024-08-17/IMG_0704.JPG" caption="We watch Wolverine and Deadpool tonight - it's a lighthearted flic, and I love it how they use the fourth wall" >}}
+  {{< gallery-photo fn="2024-08-19/IMG_0713.JPG" caption="A mostly finished PDU - with the ESP32-ETH01 in its own little box, and brackets that will hold the ammeter." >}}
+  {{< gallery-photo fn="2024-08-19/IMG_0714.JPG" caption="One side of the box will be green, the other red. This is to signify that there are two 220V C13 inputs each with their own 8 C14 plugs on the front." >}}
+  {{< gallery-photo fn="2024-08-18/fusion.png" caption="The fusion design - top right has what I call the floorplan, with the individual screw holes and pegs of the chassis. THe other things are the parts that go within." >}}
+  {{< gallery-photo fn="2024-08-18/IMG_0710.JPG" caption="We watched Jared Leto and Jennifer Connelley in Requiem for a Dream." >}}
+  {{< gallery-photo fn="2024-08-18/IMG_0711.JPG" caption="The two loaves of bread baked themselves on a timer!" >}}
+  {{< gallery-photo fn="2024-08-18/IMG_0712.JPG" caption="Another tray of parts is freshly printed in black PLA. I will need to make eight batches of these." >}}
+  {{< gallery-photo fn="2024-08-19/IMG_0713.JPG" caption="The innards of the PDU are nicely placed in 3D printed parts." >}}
+  {{< gallery-photo fn="2024-08-19/IMG_0716.JPG" caption="The Rigol oscilloscope cannot see a problem with the differential RS485 signal." >}}
+  {{< gallery-photo fn="2024-08-19/IMG_0718.JPG" caption="I play around a little bit with the Sipeed NanoKVM" >}}
+  {{< gallery-photo fn="2024-08-19/IMG_0719.JPG" caption="The Sipeed NanoKVM shows a 1920x1080p picture from my Linux PC, Summer" >}}
+  {{< gallery-photo fn="2024-08-19/sipeed-kvm.png" caption="A screenshot of Summer's desktop as seen in a web browser, using Sipeed's NanoKVM over IP" >}}
+  {{< gallery-photo fn="2024-08-19/IMG_0720.JPG" caption="We eat Flammkuchen tonight, courtesy of Marina" >}}
+  {{< gallery-photo fn="2024-08-19/IMG_0721.JPG" caption="Leave your phone unattended, and there will be goofy pictures when you return..." >}}
+
 {{< /gallery-category >}}
 
 ### Playing with OBS sound (August 8th)