I am using NetFIELD 32GB Gateway with Version 2.2.0.0 for Modbus RTU communication to take the data from Energy Meter & other field devices using our NIOT-E-NPIX-RS485 (Rev2 module).
Energy Meter and other field devices got disconnected for a few seconds and connect back again this is happing randomly. attached screenshot.
Hilscher netPi Node-red installed from docker - version 1.7.6
Question 1: is only the communication interrupted or is the whole Node-RED stopping for a split of a second?
Question 2: I see a lot of Modbus RTU nodes running at a time in your flow. I don't know how exactly the serial node is working since Hilscher is not the programmer. But what is if ALL nodes want to send out data at exaclty the same time to the RS485 interface? Maybe the nodes are not locked against each other ... and then nonsense is sent to serial port due to parallel access. In Modbus TCP this is no problem since Ethernet frames are sent ... but with Modbus RTU this is a single physical resource that cannot be shared. So I think you have to change your complete flow to use a single Modbus RTU node only. And also you have to implement a mechanism using the Topics feature in a node message to distingush the different messages from each other
Thx
Armin
„You never fail until you stop trying.“, Albert Einstein (1879 - 1955)
(February-1st-2022, 08:26 AM)Armin@netPI Wrote: Well Devendra,
Question 1: is only the communication interrupted or is the whole Node-RED stopping for a split of a second?
Question 2: I see a lot of Modbus RTU nodes running at a time in your flow. I don't know how exactly the serial node is working since Hilscher is not the programmer. But what is if ALL nodes want to send out data at exaclty the same time to the RS485 interface? Maybe the nodes are not locked against each other ... and then nonsense is sent to serial port due to parallel access. In Modbus TCP this is no problem since Ethernet frames are sent ... but with Modbus RTU this is a single physical resource that cannot be shared. So I think you have to change your complete flow to use a single Modbus RTU node only. And also you have to implement a mechanism using the Topics feature in a node message to distingush the different messages from each other
Thx
Armin
Dear Armin,
Please find below my reply.
Question 1: yes whole node-red stopping for a split of a second.
Well if it is node-red stopping completely as you say which means also the rest of node-red stops during the failure ... for this I cannot help. Node-RED is a 3rd party tool hilscher is not giving any support for. What I san say for sure ... a stopping node-red has nothing to do with the RS485 but with a software related problem only.
„You never fail until you stop trying.“, Albert Einstein (1879 - 1955)
I think there is a misunderstanding Node-red Modbus RTU flow is stoping only not the whole node-red application.
Now I have plugged RS485 into the USB converter which we used earlier and connected it to the NetFIELD gateway USB port, I just change the interface type from our NIOT-E-NPIX-RS485 module to USB and it is running continuously, same field devices connected.
The observation is below.
With RS485 to USB converter - Running Continuously even in multi-drop.
With our NIOT-E-NPIX-RS485 module - Not Running Continuously randomly communication breaking in muti drop, but with the single device it is working continuously.
Well Devendra, RS485 to USB converter is an intelligent device with queuing mechanism. A direct converter as NPIX works different. It immediately sends out data without queuing it since you are "on the hardware" level and the "dumb" driver chip applied on the NPIX RS485 is just acting each bit by bit transparently.
To verify what I am saying just insert a single Modbus RTU node only and only use this one with a single command and you will see that it will work forever with charme and without hanging.
Thx
Armin
„You never fail until you stop trying.“, Albert Einstein (1879 - 1955)
Now the issue is resolved in multi-dropping communication, Modbus devices communicate continuously after changing the Queue delay in the Modbus node. please find attached a screenshot.
If I connect multiple devices or add multiple Modbus Read requests I have to manage Queue delay, i.e devices increase or command increases we have to increase Queue delay accordingly.
