# FX30S Set GPIO56/IO3 to current sink

**URL:** <https://forum.sierrawireless.com/t/fx30s-set-gpio56-io3-to-current-sink/21995>\
**Category:** FX30\
**Created:** [November 2, 2020, 8:37pm UTC](https://forum.sierrawireless.com/t/fx30s-set-gpio56-io3-to-current-sink/21995 "2020-11-02T20:37:53Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![einarsundgren](https://avatars.discourse-cdn.com/v4/letter/e/c68b51/32.png) [@einarsundgren](https://forum.sierrawireless.com/u/einarsundgren)\
**Post date:** [November 2, 2020, 8:37pm UTC](https://forum.sierrawireless.com/t/fx30s-set-gpio56-io3-to-current-sink/21995/1 "2020-11-02T20:37:53Z")

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According to the FX30S user guide R6 IO3/Gpio56 can be used to drive a load of \<400mA. The device is running Legato 18.06.

So from the diagram I assume that +5-+36V from the power connector to IO3 should be able to drive a relay.

It should also be done with pullups off according to the user guide.

I have tried this but the multimeter (Amp range) between IO3 and Pin1 in the power connector shows nothing, reagrdless of the state of gpio56.

With pull ups on I get a response from the pin sending out +/-5V, but the drained amps are still displaying 0.

Any clue what I am doing wrong?

Edit:  
It should also be noted that when I try to set the GPIO to tristate/open drain or enable/disable resistors using the API I get errors:

> Open Drain API not implemented in sysfs GPIO  
> Tri-State API not implemented in sysfs GPIO  
> Disabling the resistors is not supported

Though accessing Gpio54 directly allows med to control the reisistors.

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**Author:** ![Donald](https://avatars.discourse-cdn.com/v4/letter/d/ac8455/32.png) [@Donald](https://forum.sierrawireless.com/u/Donald)\
**Post date:** [November 3, 2020, 3:16am UTC](https://forum.sierrawireless.com/t/fx30s-set-gpio56-io3-to-current-sink/21995/2 "2020-11-03T03:16:18Z")

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Hi @einarsundgren

Please try using AT!FWD?GPIO, AT!FWD=GPIO, AT!FWD?GPIOCFG, AT!FWD=GPIOCFG commands to control the GPIO56/IO3.