TC-08 single channel terminal board 0-5v signal reading quite low

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Joined: Fri Jul 16, 2021 2:38 am
Location: Weyburn, Saskatchewan, Canada

TC-08 single channel terminal board 0-5v signal reading quite low

Post by Blake »

I am a new user attempting to use a new USB TC-08 with single channel TC-08 Terminal boards to measure 0-5vdc signal. My issue is that the value displayed on PICOLOG 6 shows about 1.5vdc when a clear continuous 5vdc signal is applied to the input (+5vdc connected to the "4-20/5v" & earth connected to "COM", yellow switch "OFF")

The 5vdc signal is derived using a basic voltage divider resistor circuit to lower the voltage from 25vdc to 5vdc. R1=10kΩ, R2=2.5kΩ. R1is connected to +25vdc, R2 is connected to R1 in series and then connected to ground. With R1&R2 connected in series the +5vdc signal to the TC08 comes from the junction of R1&R2 while the "COM" is connected to ground at the same point as R2.

This set up is simply to familiarize myself with the TC-08 single channel terminal board. My real goal is to use a similar set up to log several 24vdc PWM 150hz inductive actuator circuits, in addition to 0.5-4.5vdc signals from pressure transducers.

I have tried restarting my computer, rebooting Picolog 6, reinstalling picolog 6, trying different channels on the TC-08, trying other single channel terminal boards & trying other TC-08 USB dataloggers. I have verified the signal voltage with 2 meters, used other much lower Ω and much higher Ω resistor combinations to achieve between 3-5vdc signal but the display reading is always quite low compared to my meters.

I appreciate any assistance you can offer. Thank You.

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