I do not have a Pi and do not know what you would use to connect any particular Pi model to RS232. I can’t imagine it’s very demanding or unusual though.
ordered a rs232 shield for the raspi.
i’ll keep you posted!
Alright!
Got my serial pi plus and installed it according to this: https://www.abelectronics.co.uk/kb/article/1035/raspberry-pi-3-and-zero-w-serial-port-usage
i activated the 1.9 Modbus Binding in OH2 and now i’m wondering what to do next…
first (and only) thing i did with the Modbus Binding was setting:
# (slave name) (host or IP)
# | | (baud)
# | | | (dataBits)
# | | | | (parity)
# | | | | | (stopBits)
# | | | | | | (encoding)
# | | | | | | | (interTransactionDelayMillis)
# | | | | | | | | (receiveTimeoutMillis)
# | | | | | | | | | (flowControlIn)
# | | | | | | | | | | (flowControlOut)
# | | | | | | | | | | |
# | | | | | | | | | | |
#serial.slave1.connection=/dev/ttyS0:38400:8:none:1:rtu:35:1500:none:none
serial.slave1.connection/dev/tty1:9600:8:none:1:rtu:35:1500:none:none
host according to the tutorial ob abelectronics
baud, databits, parity, stopbits according to manufacturer manual
rtu because it’s called “Modbus RTU”
interTransactionDelayMillis, receiveTimeoutMillis, flowControlIn, flowControlOut like example?
what’s net next step?
how can i test the setup?
there’s tons of information in manual and in a “parameters” file (german)
http://gasserenergy.ch/wp-content/uploads/2015/09/900.6660_01_TI_Modbus_RTU_DE.pdf
http://filter.drexel-weiss.at/HP/Upload/Dateien/900.6667_00_TI_Modbus_Parameter_V4.01_DE.pdf
Start simple
You need to cable Pi wires TX to heating RX, Pi RX to heating TX, Pi 0v to heating 0v
I think I see in the docs that the heating responds to Modbus commands x04 (FC4 read input reg) and x10 (FC16 write multiple regs) - so will need to set writemultipleregisters = true for later, if you are going to alter settings in the heater
You’ll need to complete your modus.cfg set up for slave1
You need to find the Modbus slave ID for your heater, still at default perhaps.
Choose a simple register to read, register 202 looks promising - air temperature is that?
Find out the format of that register - I guess it might be 32-bit signed
All that should allow you to set id, start, length, type parameters
When slave1 is configured in modbus.cfg, you can set up an Item in your .items file to hold the data.
It’ll need to be a Number type, and you configure it in the curly bracket {} to look at the first register you defined for slave1
rpi - heating is wired like you mentioned (0v =gnd?)
ID for my heater is 2.
Register 202 is air temperature!
now - how do i found out the format of that register? as i understand parameter goes from -28000 to 10000 with a divisor of 100, 1 comma and unit °C.
On page 10/16 of the first pdf there is an example of how to make a request (“Register lesen”) for register 1184.
On page 13/16 it says that all values are “signed int” and there’s also an explanation of how to convert the register 202 value: Register 202 --> Wert (value) 22500 / 100 = 225 --> Darstellung mit 1 Kommastelle = 22,5 °C
could you please explain / show me how i could set the parameters in modbus.cfg?
this is all to new for me 
I’m not doing it for you, but will offer help.
You should already have your guide, but there is a lot in it
You can see more sample Modbus slave definitions, like you want to use in modbus.cfg, here
You should have everything you need to set up your first Modbus slave, apart from this part
Modbus numbers always come in 16-bit registers (words) over the protocol , but there are different ways to interpret 16-bit registers and/or combine them into e.g. 32-bit registers.
Looking at page 13/16 it suggests that reading one data value from the D&W is returned as 4 bytes, that is two 16-bit Modbus words, together representing a 32-bit signed integer.
I think the datatype your modbus slave requires will be 32 bit signed int. With that knowledge, you might find more mention of that fact in the manual.
Bearing in mind 32 bits is two Modbus words, you need to double the config length parameter - for your starter case to read one temperature, use length 2
Have a try, and show us what your modbus.cfg looks like
I don’t know how many times i tried to understand the off. Modbus binding page.
i don’t get that at all. as i previously mentioned Modbus is completely new.
Reading the Modbus binding page confuses me more and more.
type:
[quote]type=coil uses function 1 “Read Coil Status”
type=discrete uses function 2 “Read Input Status” (readonly inputs)
type=holding uses function 3, “Read Holding Registers”
type=input uses function 4 “Read Input Register” (readonly-registers eG analogue inputs)[/quote]
[quote]In the traditional standard, [entity] numbers for those entities start with a digit, followed by a number of four digits in range 1–9,999:
coils numbers start with a zero and then span from 00001 to 09999
discrete input numbers start with a one and then span from 10001 to 19999
input register numbers start with a three and then span from 30001 to 39999
holding register numbers start with a four and then span from 40001 to 49999
This translates into entity addresses between 0 and 9,998 in data frames.
The openhab modbus binding uses data frame entity addresses when referring to modbus entities. That is, the entity address configured in modbus binding is passed to modbus protocol frame as-is. For example, modbus slave definition with start=3, length=2 and type=holding will read modbus entities with the following numbers 40004 and 40005.[/quote]
i (think…) i understand why the modbus slave definition reads modbus entities 40004 and 40005, but i absolutely don’t geht where these numbers point to?
Let’s stay with the example on page 10 of my first pdf…
Anfrage = request / Anwort = response / last row: it’s possible / mandatory to read 2 registers (?!)
should i be able to geht all the informations needed from this? should i look at the request or response seciton? HEX/DEC row?
with all that new knowledge (with extends to… not a lot) my modbus.cfg. extends to this:
serial.slave1.connection/dev/tty1:9600:8:none:1:rtu
serial.slave1.length=2
i’m really not looking for anyone to set up my heating device, but as you can see i’m struggling pretty bad…
so i’d be really thankful if you had the patience to push me in the right direction…
am i even looking in the right direction (modbus entities) oder is that the wrong approach?
Greetings, very confused greetings.
The example in your PDF says the heating device is read usin function 04, also known as FC4 in modbus-speak.
Looking at the OpenHAB binding guide,
you will find only one choice for function 4.
Now you can add another line to your config. (type)
Your device’s manual does not refer to such large value addresses, you simply need not worry about it. There is a Modbus convention around 5-figure decimal addresses, but you don’t have any.
Now you can add another line to your config. (start)
Your device’s manual is showing you exactly what Modbus transactions look like. In this case, OpenHAB plays master and generates a request, the heating plays slave and generates a response,
The binding takes care of this structure, and the CRC checksum and so on, but the example is useful for extracting the details that you need to configure the binding
Already had the explanation about the “basic unit” of Modbus being a register as a 16-bit word, that is two bytes. Modbus words can be lumped together to form 32-bit words. A slave device presenting some data in the form of a 32-bit value might well say in its manual to read two registers … make sense?
This why we have length 2 in the config.
Of course OpenHAB needs to be told how the data is presented, it cannot guess.
Now you can add another line to your config (datatype)
[quote=“rossko57, post:23, topic:22379”]
you will find only one choice for function 4.
Now you can add another line to your config. (type)[/quote]
Where did you get that in the pdf?
“read input registers: FC 4 (Read Input Registers)”
(so writing would be: "write holding register: FC 6 (Write Single Holding Register), OR FC 16 (Write Multiple Holding Registers) (see note on writemultipleregisters configuration parameter below) > type=holding
serial.slave1.connection/dev/tty1:9600:8:none:1:rtu
serial.slave1.type=input
serial.slave1.length=2
i’m guessing here…
serial.slave1.start=202but it’s probably not just the register number?
[quote=“rossko57, post:23, topic:22379”]
Now you can add another line to your config (datatype)
[/quote][quote=“rossko57, post:23, topic:22379”]
A slave device presenting some data in the form of a 32-bit value might well say in its manual to read two registers[/quote]
well, i can try?
serial.slave1valuetype=int32Just because you stated it in your post - i’m not sure why…
Yep, it is usually that simple. It can get more complicated, but try simple first.
Because your D&W manual says to read two Modbus registers, that’s 2 x 16-bits, and it says the temperature is signed. So, signed 32-bit integer.
Again it can get more complicated (which of the 16-bit chunks is the high half) but lets start simple.
If you have twinkly lights on your serial interface, they should be twinkling by now. And if you look in your log, the binding may be giving you messages.
Next, to set up a Number Item to receive the data from this defiined slave.
modbus.cfg:
serial.slave1.connection/dev/tty1:9600:8:none:1:rtu
serial.slave1.id=2
serial.slave1.type=input
serial.slave1.length=2
serial.slave1.start=202
serial.slave1.valuetype=int32
id = 2 because heating has id 2 in the heaters system (while id 1 is air circulation module) ?
item.
“0” means start+0 / 202+0 = 202, right?
Yes, 0 means first (and only) of 32-bit chunks defined by slave1
Item type is Number though, these things matter.
I don’t have enough German to confirm what the ID should be.
Things should be happening - logs, twinkly lights, value of Temp1 in your sitemap?
2017-03-29 18:34:05.584 [ERROR] [ing.ModbusSlaveConnectionFactoryImpl] - connect try 1/3 error: Modbus serial device doesn't exist!. Connection SerialConnection@936bf6[portName=,port=<null>]. Endpoint ModbusSerialSlaveEndpoint@e79cf3[portName=]
2017-03-29 18:34:05.585 [ERROR] [ing.ModbusSlaveConnectionFactoryImpl] - connect try 2/3 error: Modbus serial device doesn't exist!. Connection SerialConnection@936bf6[portName=,port=<null>]. Endpoint ModbusSerialSlaveEndpoint@e79cf3[portName=]
2017-03-29 18:34:05.585 [ERROR] [ing.ModbusSlaveConnectionFactoryImpl] - connect try 3/3 error: Modbus serial device doesn't exist!. Connection SerialConnection@936bf6[portName=,port=<null>]. Endpoint ModbusSerialSlaveEndpoint@e79cf3[portName=]
2017-03-29 18:34:05.586 [ERROR] [ing.ModbusSlaveConnectionFactoryImpl] - re-connect reached max tries 3, throwing last error: Modbus serial device doesn't exist!. Connection SerialConnection@936bf6[portName=,port=<null>]. Endpoint ModbusSerialSlaveEndpoint@e79cf3[portName=]
2017-03-29 18:34:05.586 [ERROR] [ing.ModbusSlaveConnectionFactoryImpl] - Error connecting connection SerialConnection@936bf6[portName=,port=<null>] for endpoint ModbusSerialSlaveEndpoint@e79cf3[portName=]: Modbus serial device doesn't exist!
2017-03-29 18:34:05.587 [WARN ] [.binding.modbus.internal.ModbusSlave] - ModbusSlave (slave1): Error getting a new connection for endpoint ModbusSerialSlaveEndpoint@e79cf3[portName=]. Error was: Unable to validate object
2017-03-29 18:34:05.588 [WARN ] [.binding.modbus.internal.ModbusSlave] - ModbusSlave (slave1) not connected -- aborting read request net.wimpi.modbus.msg.ReadInputRegistersRequest@9942ae. Endpoint ModbusSerialSlaveEndpoint@e79cf3[portName=]
can’t connect to slave…
pi is losing connection (wired) very often. there’s something very very wrong here… probably there’s a problem with my serial device…
I think you are missing equals sign in the connection line. Instead of
serial.slave1.connection/dev/tty1:9600:8:none:1:rtu
You should have
serial.slave1.connection=/dev/tty1:9600:8:none:1:rtu
Best
Sami
1 Like
You mean ethernet?
How is the Pi powered - you have added a new device load (serial port).
Where is the Pi located, not in amongst electrical noisy heating switching cabling.
Is it better if you disconnect the serial cable to the heating - there may be some earth loop via the ground wire.
removing modbus.cfg was all i did to get the pi working as usual
i really missed the equal signs 
now there are different errors and warnings…
2017-03-29 20:50:39.949 [WARN ] [.binding.modbus.internal.ModbusSlave] - ModbusSlave (slave1): Error getting a new connection for endpoint ModbusSerialSlaveEndpoint@11b2f2e[portName=/dev/tty1]. Error was: Unable to validate object
2017-03-29 20:50:39.950 [WARN ] [.binding.modbus.internal.ModbusSlave] - ModbusSlave (slave1) not connected -- aborting read request net.wimpi.modbus.msg.ReadInputRegistersRequest@9dd0ca. Endpoint ModbusSerialSlaveEndpoint@11b2f2e[portName=/dev/tty1]
2017-03-29 20:50:40.152 [ERROR] [et.wimpi.modbus.net.SerialConnection] - Could not get port identifier, maybe insufficient permissions. null
2017-03-29 20:50:40.154 [ERROR] [ing.ModbusSlaveConnectionFactoryImpl] - connect try 1/3 error: Could not get port identifier, maybe insufficient permissions. null. Connection SerialConnection@18aa26d[portName=/dev/tty1,port=<null>]. Endpoint ModbusSerialSlaveEndpoint@11b2f2e[portName=/dev/tty1]
2017-03-29 20:50:40.190 [ERROR] [et.wimpi.modbus.net.SerialConnection] - Could not get port identifier, maybe insufficient permissions. null
2017-03-29 20:50:40.191 [ERROR] [ing.ModbusSlaveConnectionFactoryImpl] - connect try 2/3 error: Could not get port identifier, maybe insufficient permissions. null. Connection SerialConnection@18aa26d[portName=/dev/tty1,port=<null>]. Endpoint ModbusSerialSlaveEndpoint@11b2f2e[portName=/dev/tty1]
2017-03-29 20:50:40.228 [ERROR] [et.wimpi.modbus.net.SerialConnection] - Could not get port identifier, maybe insufficient permissions. null
2017-03-29 20:50:40.229 [ERROR] [ing.ModbusSlaveConnectionFactoryImpl] - connect try 3/3 error: Could not get port identifier, maybe insufficient permissions. null. Connection SerialConnection@18aa26d[portName=/dev/tty1,port=<null>]. Endpoint ModbusSerialSlaveEndpoint@11b2f2e[portName=/dev/tty1]
2017-03-29 20:50:40.230 [ERROR] [ing.ModbusSlaveConnectionFactoryImpl] - re-connect reached max tries 3, throwing last error: Could not get port identifier, maybe insufficient permissions. null. Connection SerialConnection@18aa26d[portName=/dev/tty1,port=<null>]. Endpoint ModbusSerialSlaveEndpoint@11b2f2e[portName=/dev/tty1]
2017-03-29 20:50:40.231 [ERROR] [ing.ModbusSlaveConnectionFactoryImpl] - Error connecting connection SerialConnection@18aa26d[portName=/dev/tty1,port=<null>] for endpoint ModbusSerialSlaveEndpoint@11b2f2e[portName=/dev/tty1]: Could not get port identifier, maybe insufficient permissions. null
2017-03-29 20:50:40.232 [WARN ] [.binding.modbus.internal.ModbusSlave] - ModbusSlave (slave1): Error getting a new connection for endpoint ModbusSerialSlaveEndpoint@11b2f2e[portName=/dev/tty1]. Error was: Unable to validate object
2017-03-29 20:50:40.233 [WARN ] [.binding.modbus.internal.ModbusSlave] - ModbusSlave (slave1) not connected -- aborting read request net.wimpi.modbus.msg.ReadInputRegistersRequest@17bbfef. Endpoint ModbusSerialSlaveEndpoint@11b2f2e[portName=/dev/tty1]
2017-03-29 20:50:40.435 [ERROR] [et.wimpi.modbus.net.SerialConnection] - Could not get port identifier, maybe insufficient permissions. null
2017-03-29 20:50:40.435 [ERROR] [ing.ModbusSlaveConnectionFactoryImpl] - connect try 1/3 error: Could not get port identifier, maybe insufficient permissions. null. Connection SerialConnection@1892005[portName=/dev/tty1,port=<null>]. Endpoint ModbusSerialSlaveEndpoint@11b2f2e[portName=/dev/tty1]
2017-03-29 20:50:40.471 [ERROR] [et.wimpi.modbus.net.SerialConnection] - Could not get port identifier, maybe insufficient permissions. null
2017-03-29 20:50:40.472 [ERROR] [ing.ModbusSlaveConnectionFactoryImpl] - connect try 2/3 error: Could not get port identifier, maybe insufficient permissions. null. Connection SerialConnection@1892005[portName=/dev/tty1,port=<null>]. Endpoint ModbusSerialSlaveEndpoint@11b2f2e[portName=/dev/tty1]
2017-03-29 20:50:40.509 [ERROR] [et.wimpi.modbus.net.SerialConnection] - Could not get port identifier, maybe insufficient permissions. null
2017-03-29 20:50:40.510 [ERROR] [ing.ModbusSlaveConnectionFactoryImpl] - connect try 3/3 error: Could not get port identifier, maybe insufficient permissions. null. Connection SerialConnection@1892005[portName=/dev/tty1,port=<null>]. Endpoint ModbusSerialSlaveEndpoint@11b2f2e[portName=/dev/tty1]
2017-03-29 20:50:40.510 [ERROR] [ing.ModbusSlaveConnectionFactoryImpl] - re-connect reached max tries 3, throwing last error: Could not get port identifier, maybe insufficient permissions. null. Connection SerialConnection@1892005[portName=/dev/tty1,port=<null>]. Endpoint ModbusSerialSlaveEndpoint@11b2f2e[portName=/dev/tty1]
2017-03-29 20:50:40.511 [ERROR] [ing.ModbusSlaveConnectionFactoryImpl] - Error connecting connection SerialConnection@1892005[portName=/dev/tty1,port=<null>] for endpoint ModbusSerialSlaveEndpoint@11b2f2e[portName=/dev/tty1]: Could not get port identifier, maybe insufficient permissions. null
2017-03-29 20:50:40.512 [WARN ] [.binding.modbus.internal.ModbusSlave] - ModbusSlave (slave1): Error getting a new connection for endpoint ModbusSerialSlaveEndpoint@11b2f2e[portName=/dev/tty1]. Error was: Unable to validate object
2017-03-29 20:50:40.512 [WARN ] [.binding.modbus.internal.ModbusSlave] - ModbusSlave (slave1) not connected -- aborting read request net.wimpi.modbus.msg.ReadInputRegistersRequest@1a4a17e. Endpoint ModbusSerialSlaveEndpoint@11b2f2e[portName=/dev/tty1]
2017-03-29 20:50:40.714 [ERROR] [et.wimpi.modbus.net.SerialConnection] - Could not get port identifier, maybe insufficient permissions. null
2017-03-29 20:50:40.714 [ERROR] [ing.ModbusSlaveConnectionFactoryImpl] - connect try 1/3 error: Could not get port identifier, maybe insufficient permissions. null. Connection SerialConnection@195ee2d[portName=/dev/tty1,port=<null>]. Endpoint ModbusSerialSlaveEndpoint@11b2f2e[portName=/dev/tty1]
yay
I’m pretty sure i’m having a problem with the serial device…
this is what i get after a clean jessie install and following http://spellfoundry.com/2016/05/29/configuring-gpio-serial-port-raspbian-jessie-including-pi-3/#Using_the_serial_port_with_other_hardware
pi@raspberrypi:~ $ ls -l /dev
lrwxrwxrwx 1 root root 7 Mar 29 18:29 serial0 -> ttyAMA0
lrwxrwxrwx 1 root root 5 Mar 29 18:29 serial1 -> ttyS0
but with my openHABian image there’s no serial …
Might be permissions issue, i have no idea about unix, you need someone else’s help.
There are quite a few threads touching on this here if you search.
OpenHAB2 seems to have an unpleasant habit of caching config, ‘removing’ things does not remove them.
posted my problem in openHABian related threat. i hope to resolve this issue and be back soon!
thank you very much in the meantime!
Mind you, your config asks for tty1 and you don’t have one … ttyS0 ?
1 Like
sadly there’s no tty* 