RS485/RS232/Serial transport class for mysensors.org

Bart

I was able to solve that long initialization problem with removing AltSoftSerial completely and using another Mega board on Serial1 serving as a GW. It looks like the AltSoftSerial on Nano was not working well with Serial1 on Mega.

Strange that although now it works almost instantly, the reading of data from the HA takes longer than before... Not sure what could be causing this.

It looks that these RS485 modules have the resistors already added between A and B cables and +5 and GND so I don't think that could be an issue.

hek

Thanks for the feedback.

So how should the modules be inter-connected? Do you have time to create some drawing for the instruction page?

Bart

@hek
I will do the schematic once I solve all issues as I am still losing events while connected to Home Assistant. Need to check whether it is because of pymysensors library (Home Assistant side) or if there is still some GW <-> Sensors problem. At this moment my Sensors board has around 48 binary states one can set/read from the controller and at the same time they are changeable via input pins (falling edge toggles the switch).

To give a quick overview of my setup:

2 x (MEGA 2560 + RS485 module)
alt text

I have the following connections for each mega+rs485 module:

+5/GND connected to respective pins on rs485 module
D2 connected to RE/DE
D18 <-> RO
D19 <-> DI

The A and B lines are connected to each other. (A-A, B-B). And most importantly I am using the above mentioned minor change in the MyTransportRS485.cpp to replace altSoftSerial with Serial1 (https://forum.mysensors.org/topic/1947/rs485-rs232-serial-transport-class-for-mysensors-org/99)

and just if anyone would like to try it here's the config I am using:

// Gateway:
#define MY_RS485
#define MY_RS485_DE_PIN 2
#define MY_RS485_BAUD_RATE 9600
#define MY_GATEWAY_SERIAL
// below not official for getting the Serial1
#define MY_RS485_SERIAL Serial1

// Sensor node
#define MY_DEBUG
#define MY_RS485
#define MY_RS485_DE_PIN 2
#define MY_RS485_BAUD_RATE 9600
// below not official for getting the Serial1
#define MY_RS485_SERIAL Serial1

karlheinz2000

@Bart
Does it work with serial1 on mega2560?

I can't get a single bit out of the harware serial1.
Is it only the smal patch in MyTransportRS485.cpp?

Bart

@karlheinz2000
Yes. Got it working with this patch. Although not reliably when other board was using the altsoftserial.

karlheinz2000

Got it working too :smile:
Problem was: RX1 and TX1 labels on the chinese Mega2560 board are swapped. :angry:
All other RX/TX labels are right.

Bart

@karlheinz2000 Are any of your boards using AltSoftSerial instead of HW serial? I was not able to get a reliable connection with software serial library....

karlheinz2000

I use a mega with hw-serial and a nano (gateway) with AltSoftSerial.
It works fine the last 24 hours. Still running...
I did not test other configurations.

Bart

@hek Looks like something has been fixed in regards to altSoftSerial. Today I've pulled latest development and everything works fine. The gateway has no problem finding nodes and all messages reach their destinations.

hek

Hmm, strange. Wonder if this PR affected the behaviour of AltSoftSerial (in a good way).

https://github.com/mysensors/MySensors/pull/599

Bart

@hek I will try to check if this change did it.

Bart

I am wondering if a node-2-node communication should be working. I have compiled the ping/pong example for RS485 but it appears the nodes are not communicating.

hek

Did you set one of them to be repeater (or gateway)?

Bart

@hek ok. all good now - the ping pong example working. I forgot about the gateway flag.

BTW, checked to see if the GW has any issues without PR 599 but it seems it is still working OK. I have not changed the HW connections so must be some other change.

karlheinz2000

Is any data buffer/FIFO implemented in RS485 gateway?
My controller (fhem) is transmitting data too fast to the gateway, so some data is not transmitted on RS485.
I checked RX/TX from controller to gateway -> all data is going into gateway. But not all data goes out to my sensor node.

I have only one sensor (and gateway) on RS485.
Baudrate is 19200 on RS485 and to controller.
Sensor node uses HW serial. Gateway is on NANO with AltSoftSerial.

LeoDesigner

@karlheinz2000
I had no chance to look to the AltSoftSerial code, but if we are talking about hardware serial - arduino as a standard has 64 bytes buffer. I think it's possible that your gateway is not fast enough to process packets at high rate from FHEM. Also even if they are processed on time - at 19200 you may loose packets due low serial speed. It's simple no room for next packet.

karlheinz2000

@LeoDesigner
I did a hardware update. Now sensor and gateway are arduino mega. Everything is running on 115200 hardware serial.
RS485 communication looks good. Data is going into sensor node, but does not appear in MySensors.
I tried to increase RX buffer via #define SERIAL_RX_BUFFER_SIZE 256, with no effect in functionality. Does this define works as expected? Because this buffer size number has no effect on the 'dynamic memory' usage after compiling the sketch. It shows always the same number of used bytes, independent of the RX buffer size.

karlheinz2000

[Solved]
Initial Problem were incoming messages at sensor node during reading an image from SD card (170ms). Increase of serial RX buffer size solved the problem.

Good to know:
The serial buffer size is not defined in:
c:\Program Files (x86)\Arduino\hardware\arduino\avr\cores\arduino\HardwareSerial.h
You can change the numbers with no effect to your sketch.

You have to change:
c:\Users...\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.14\cores\arduino\HardwareSerial.h

Then it will work :smiley:

AndrewZ

I'm curious whether it is possible to use this RS485 transport with Ethernet or MQTT gateway or Serial gateway is the only option?
For example, controller talks with MySensors Gateway over Ethernet,
MySensors Gateway talks with the Nodes over RS485.
Thanks!

hek

@AndrewZ

Yes, that should work just fine.

RS485/RS232/Serial transport class for mysensors.org

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