Reply To: Keller CTD Sensor

Something to note, a bit strange, is it comes up in SDI-12 mode, and needs an initial configuration to switch

Something to note, a bit strange, is it comes up in SDI-12 mode, and needs an initial configuration to switch to RS485.
From getting some initial success – it may be worth starting with SDI-12 and getting some responses. Alternatively talk with a tech rep as to how they see this can be configured to RS485 before purchase.

https://keller-druck.com/en/products/level-probes/multi-parameter-probes/series-36xiw-ctd

Then in the Manual https://download.keller-druck.com/api/download/yRqtkpbcVNQDHa3i7zdXDm/en/2020-04.pdf
As well as the standard RS485 interface, which provides access to
all configuration registers, the pressure level transmitter can also be
ordered with an SDI-12 interface. Only one interface will be active at
any one time. Corresponding commands are used to switch between
interfaces (default setting on delivery: SDI-12).

From SDI12 manual ~ https://download.keller-druck.com/api/download/KMkeowTYmcRcUyZfadRVvZ/en/2015-11.pdf
7 Switch to RS485 (Kellerbus)
It is possible to switch from SDI-12 mode to the Kellerbus-mode (RS485 communication, Kellerbus or MODBUS RTU):
Description Command Response
Switch to RS485 (Kellerbus) aXC! aXC02Fe13! aXCD<CR><LF> (successful)
aXCE<CR><LF> (not successful)
After this command it is not possible to communicate over SDI-12 bus with the transmitter any more.
Be sure to have all hardware equipment for Kellerbus (RS485) available and the according software before switching SDI-12 off.
There is always only one communication interface active and the hardware of the other interface is switched of meanwhile and
can only be activated over a software command.