# AIO adapter doesn't return expected values for current loop without 250ohm resistor to ground.

**URL:** <https://forums.digi.com/t/aio-adapter-doesnt-return-expected-values-for-current-loop-without-250ohm-resistor-to-ground/15144>\
**Category:** XBee - Zigbee\
**Tags:** aio, 4-20ma, current-loop\
**Created:** [July 26, 2015, 5:46pm UTC](https://forums.digi.com/t/aio-adapter-doesnt-return-expected-values-for-current-loop-without-250ohm-resistor-to-ground/15144 "2015-07-26T17:46:42Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![acervantes](https://avatars.discourse-cdn.com/v4/letter/a/839c29/32.png) [@acervantes](https://forums.digi.com/u/acervantes)\
**Post date:** [July 26, 2015, 5:46pm UTC](https://forums.digi.com/t/aio-adapter-doesnt-return-expected-values-for-current-loop-without-250ohm-resistor-to-ground/15144/1 "2015-07-26T17:46:42Z")

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I thought there was supposed to be an internal resistor for the purpose of measuring the voltage drop for analog conversion.

I’ve verified the sensor is returning the expected 4ma but I get a valued from the AIO of 540. I would expect to see around 175 given the formula from the Digi python libraries.

Does the internal resistor not exist in all hardware versions or does it need to be enabled through a specific config/firmware?

Here is my current config for the AIO.

Configuration of device:

```
   aggregation (AR): 255 (x 10 sec)
     assoc_led (LT): 0 (x 10 msec)
broadcast_hops (BH): 0
    cluster_id (CI): 0x11

```

conflict\_reports (CR): 3  
dest\_addr (DH/DL):  
dest\_endpoint (DE): 0xe8  
dio0\_config (D0): 2  
dio1\_config (D1): 2  
dio2\_config (D2): 2  
dio3\_config (D3): 2  
dio4\_config (D4): 4  
dio5\_config (D5): 1  
dio6\_config (D6): 4  
dio7\_config (D7): 4  
dio8\_config (D8): 4  
dio10\_config (P0): 4  
dio11\_config (P1): 3  
dio12\_config (P2): 4  
dio13\_config (P3): 5  
dio\_detect (IC): 0x0 (bitfield)  
discover\_timeout (NT): 60 (x 100 msec)  
encrypt\_enable (EE): 0  
encrypt\_options (EO): 0x0 (bitfield)  
ext\_pan\_id (ID): 0x0000000000000000  
join\_time (NJ): 255 (sec)  
join\_notification (JN): 0  
join\_verification (JV): 0  
link\_key (KY):  
max\_hops (NH): 30  
network\_watchdog (NW): 0 (min)  
node\_id (NI): Well Monitor  
polling\_rate (PO): 0 (x 10 msec)  
power\_level (PL): 4  
power\_mode (PM): 1  
pullup\_enable (PR): 0x1fff (bitfield)  
rssi\_timer (RP): 40 (x 100 msec)  
sample\_rate (IR): 10000 (msec)  
scan\_channels (SC): 0x3fff (bitfield)  
scan\_duration (SD): 3 (exponent)  
sleep\_count (SN): 1  
sleep\_mode (SM): 0  
sleep\_options (SO): 0x0 (bitfield)  
sleep\_period (SP): 32 (x 10 msec)  
sleep\_time (ST): 5000 (msec)  
source\_endpoint (SE): 0xe8  
stack\_profile (ZS): 0  
supply\_threshold (V+): 2000 (mvolts)  
wake\_host\_delay (WH): 0 (msec)

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<div class="post-metadata">

**Author:** ![mvut](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.digi.com/mvut/32/31_2.png) [@mvut](https://forums.digi.com/u/mvut)\
**Post date:** [September 14, 2015, 3:19pm UTC](https://forums.digi.com/t/aio-adapter-doesnt-return-expected-values-for-current-loop-without-250ohm-resistor-to-ground/15144/2 "2015-09-14T15:19:17Z")

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Most modules have an internal pull up and pull down resistor that you can control. From the sounds of it, you don’t have that pins pull up enabled.

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**Author:** ![FDSWireless](https://avatars.discourse-cdn.com/v4/letter/f/7c8e57/32.png) [@FDSWireless](https://forums.digi.com/u/FDSWireless)\
**Post date:** [October 27, 2015, 8:55pm UTC](https://forums.digi.com/t/aio-adapter-doesnt-return-expected-values-for-current-loop-without-250ohm-resistor-to-ground/15144/3 "2015-10-27T20:55:46Z")

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Did you ever get this worked out? i’m having a similar problem and have had no luck figuring it out. I’m receiving a reading of over 20mA from my xbee adapter at the gateway but when I test the circuit with a meter I am seeing 4mA being produced… Help please!

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<div class="post-metadata">

**Author:** ![acervantes](https://avatars.discourse-cdn.com/v4/letter/a/839c29/32.png) [@acervantes](https://forums.digi.com/u/acervantes)\
**Post date:** [November 11, 2015, 11:42am UTC](https://forums.digi.com/t/aio-adapter-doesnt-return-expected-values-for-current-loop-without-250ohm-resistor-to-ground/15144/4 "2015-11-11T11:42:46Z")

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I haven’t found any way of getting an accurate value without that resistor. It’s not a huge deal but I would have liked to see that in the documentation. This seems to be an unsupported legacy product.