I need to measure multiple thermistors (two-wire custom 10KOhm thermistors, short wires).
They will be measured by a CR6 logger, potentially with a CDM A116 module.
I know of the BrHalf instruction and wiring for a single half-bridge measurement - it needs two U terminals and a reference resistor and a ground connection.
The BrHalf instruction can be used with multiple thermistors, but the standard setup suggested by shortcut seems to need a separate reference resistor for each thermistor.
Vx ---- Rf1 ---- V1 ---- Rs1 ---- Gnd
Vx ---- Rf2 ---- V2 ---- Rs2 ---- Gnd
(Vx is excitation channel, Rf is reference resistor, V1 is SE voltage measurement, Rs is the thermistor, Gnd is ground)
The same Vx can be used to excite all thermistors, but a reference resistor seems to be needed for each thermistor.
I am wondering if it is possible to measure multiple thermistors, using the same reference resistor (installed at the datalogger terminals).
Gnd ---- Rf ---- V1 ---- Rs ---- Vx1
Gnd ---- Rf ---- V1 --------------- Rs ---- Vx2
etc
Since the CR6 loggers U terminals can be programmed for excitation voltage, this should be possible?
What about the CDM A116?
Thanks,
Thomas
For measuring thermistors directly on the CR6, you can use the Thermistor() instruction. It using an internal fixed resistor. The instruction requires a U pair for each thermistor.