Hi everyone. This is my first experience with Node-Red. Via node-red-contrib-modus I would like to read N registers of N devices. I know how to use these nodes to read the various registers individually, but I would like to configure a node that allows me to read about 20 registers for 200 modbus…

No, it wouldnt. Not without a split node to make the array into individual messages. Put the array into msg.payload then add a split node. PS also, put a delay node SET TO RATE LIMIT after the split, but before the function. Basically, everything i said here :point_down: [image] Steve-Mcl: …

I went ahead with the project and developed this method. The problem is that looking at the debug the data acquisition is not regular every 10 seconds as set by me, every now and then every 30, every now and then a device is not read. [ { "id": "b5c38da134e475d3", "type": "subf…

[image] Luca91: The problem is that looking at the debug the data acquisition is not regular Because ModBus protocol is a non deterministic protocol Because you read every single register 1 at a time This leads to inconsistent data (read on different scans of the PLC/Device) And multiplies …

PS: If you replace the "Build Modbus Request" function with a change node - this will be a NO-CODE solution. PS2: I did not check all details of this demo. For example, in your subflow, you addressed both "Potenza Attiva Totale" and "Potenza Reattiva Totale" to address 12040

Thanks to the immediate response. Yes, register 12040 is actually wrong, but it's not a problem, I'll solve it right away. Your flow is much simpler and more functional, the project involves more than monitoring more than two devices and this method seems more effective to me. I will try later to…

Furthermore, I understand that it is the "Build ModBus Req" node that decides which register to start from and how many to read, right? Why is there an offset of 30 instead of 15?

[image] Luca91: Why is there an offset of 30 instead of 15? Because a buffer is a byte array. This is called Buffer-Parser, but given an integer array, it auto parse it into a buffer for you. And since ModBus uses 16 bit register, Address 12015 appears in BYTE 30 The reason this is Buffer-…

[image] Hi, I went ahead based on your advice but I notice that this solution is also not functional. I see that only 4 requests come out from the first debug node reading 40 registers per request. I thought the 125 limit was per single request.

[image] Luca91: I see that only 4 requests come out from the first debug node reading 40 registers per request. I thought the 125 limit was per single request. That depends on what you have done. Or it could be some devices are finaky and wont play ball. It could be anything - but first - som…

Also, in the debug pane output the amount shown is limited to avoid overloading the browser. I think the output will end in a sequence of dots if it has been truncated.

By creating an Array of this kind, the Flex Getter node does not react var messages = [ { "fc": 3, "unitid": 2, "address": 32095, "quantity": 40 }, { "fc": 3, "unitid": 3, "address": 32095, "quantity": 40 }, { …

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Modbus massive reading

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Modbus massive reading

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