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Write Multiple Registers at once
#1
Hi,

I have a Modbus equipment that requires that 3 continuous registers must be written in the same operation ( Modbus Function Code 16 ).

Code:
...
{"name":"UI_1 Cmd Modo Func RAW"   ,"bus_datatype":"8","type":"register","datatype":"int16",     "address":33,   "read_swap":"n","writable":1 },
{"name":"UI_1 Cmd Modo Fan RAW"    ,"bus_datatype":"8","type":"register","datatype":"int16",     "address":34,   "read_swap":"n","writable":1 },
{"name":"UI_1 Cmd Setpoint"       ,"bus_datatype":"8","type":"register","datatype":"int16",     "address":35,   "read_swap":"n","writable":1 },

Is this possible to do this ?

Thank you
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#2
Datatype define how many registers are read/written. Int16 is one register, int32 two and so on.
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#3
(31.12.2020, 11:35)Daniel. Wrote: Datatype define how many registers are read/written. Int16 is one register, int32 two and so on.


Sorry, I think I didn't make myself understood.

I need to write these 3 registers in the same Write Operation ( FC16).

This way writes correctly, but one after the other:
Code:
...
{"name":"UI_1 Cmd Modo Func RAW"   ,"bus_datatype":"8","type":"register","datatype":"int16",     "address":33,   "read_swap":"n","writable":1 },
{"name":"UI_1 Cmd Modo Fan RAW"    ,"bus_datatype":"8","type":"register","datatype":"int16",     "address":34,   "read_swap":"n","writable":1 },
{"name":"UI_1 Cmd Setpoint"        ,"bus_datatype":"8","type":"register","datatype":"int16",     "address":35,   "read_swap":"n","writable":1 },


So, you are telling me that if I use just one variable with the "datatype":"int48" will it work ?

Thank you
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#4
This is not possible via profile, you have to use a script instead
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#5
(31.12.2020, 12:04)admin Wrote: This is not possible via profile, you have to use a script instead

Humm OK

Something like this ?

Have you got some documentation about the writeregisters method ?
Code:
require('luamodbus')
mb = luamodbus.tcp()
mb:open('192.168.0.1', 502)
mb:connect()

mb:writeregisters(???)

mb:close()


I have other TCP slaves via mapper. This script will be Event based. Can the communications work in parallel without trouble ?

Thank you
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#6
TCP should be ok this way, for RTU there's proxy library to use scripts together with profiles
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