Another newbie ModBus question

Setup, Configuration and Use Beginners
#1

Hi Guys,

probably another stupid question but here goes…

I’m trying to update an item (that is linked to a ModBus data channel) in a python script.

   events.postUpdate("itm_vva_ahu_01_ei_ht_req_lw", "3")

Thing is, the item receives the update but the update is not “written” to the slave (The binding does not perform an actual RTU write). If I link the item to my sitemap I can write the values manually via the sitemap, so there is nothing “wrong” with the binding or the configuration of the binding. I probably must use something else instead of postUpdate? Tips welcome.

Thanks & wash your hands often!

StevenT

#2

Only commands get passed to bindings, in general. This holds strictly true for the Modbus binding.
This is the primary difference between sending commands and posting updates.

The UI’s generate commands to Items.

#3

Thanks Rossko57, indeed, need to use sendCommand instead.

#4

If you can grasp the separation between Item command events and Item states (e.g. the updateable static bit) it will serve you wellin openHAB.