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+--- Thread: w4k fails reading modbus rtu float32 (/showthread.php?tid=6390)
w4k fails reading modbus rtu float32 - cgn - 15.04.2026
I've a eastron sdm72d modbus meter and I use the following lua code:
Code:
require('luamodbus')
mb = luamodbus.rtu()
mb:open('/dev/RS485', 9600, 'N', 8, 1, 'H') -- SDM72 nutzt 8N1
mb:setslave(20)
mb:connect()
local r1, r2 = mb:readinputregisters(70, 2)
local value = mb:readregistervalue(70, "float32")
log(r1, r2, value)
mb:close()I get the following result:
Code:
* arg: 1
* number: 16967
* arg: 2
* number: 57672
* arg: 3
* number: 0So in general the code seems to work. Why do I get a 0 for value?
The modbus register can be found here: https://data.xn--stromzhler-v5a.eu/manuals/eastron_sdm72dmv2.pdf
RE: w4k fails reading modbus rtu float32 - admin - 15.04.2026
Use mb:readinputregistervalue(). It's highly recommended to use profiles instead of scripts.