Modbus function 16 : Strange optimization

Hello all,

I’m trying to write data on a modbus salve device using the function 16.
In order to do that, I created a modbus device and the addresses I require (basically 12 Holding Registers from address 1).
In the designer, I created the 12 corresponding tags and a minimalistic script to write my data over these tags.

Tags = ["TagPath1", "TagPath2", ..., "TagPath12"]
Values  = [value1, value2, ..., value12]

system.tag.writeAll (Tags, Values)

I expected the write command to be sent in an unique instruction but it appears that the items of the request have been optimized to 6 couples of items. (See following Capture)


I had a look in the device advanced parameters but could not find any settings to change that.

My questions are:

[li]Is it the normal behavior ?[/li]
[li]Is it possible to indicate to the driver that I want a unique request ? (Function 16 is already used but only for two items. I would like this function to be used for the twelve items)[/li][/ul]

Any advice ?


Ignition 7.8.3
Java 1.8.91

I think this might actually be fixed in 7.8.4. It looks like the ticket mistakenly didn’t get a release note associated with it.