# Ma'm please help me out.I want to activate external I/O in two RCM4000 so as to transfer data from one module to other.

**URL:** <https://forums.digi.com/t/mam-please-help-me-out-i-want-to-activate-external-i-o-in-two-rcm4000-so-as-to-transfer-data-from-one-module-to-other/13202>\
**Category:** Rabbit Software\
**Tags:** rcm4000\
**Created:** [June 24, 2014, 5:57am UTC](https://forums.digi.com/t/mam-please-help-me-out-i-want-to-activate-external-i-o-in-two-rcm4000-so-as-to-transfer-data-from-one-module-to-other/13202 "2014-06-24T05:57:22Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![AISWARYA\_RAJ](https://avatars.discourse-cdn.com/v4/letter/a/e9bcb4/32.png) [@AISWARYA\_RAJ](https://forums.digi.com/u/AISWARYA_RAJ)\
**Post date:** [June 24, 2014, 5:57am UTC](https://forums.digi.com/t/mam-please-help-me-out-i-want-to-activate-external-i-o-in-two-rcm4000-so-as-to-transfer-data-from-one-module-to-other/13202/1 "2014-06-24T05:57:22Z")

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So ,should I make RCM4000 1 as slave and RCM4000 2 as master.?Can you provide the commands to activate the registers? Or can you Please tell which all registers to be activated?

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**Author:** ![trooper2](https://avatars.discourse-cdn.com/v4/letter/t/edb3f5/32.png) [@trooper2](https://forums.digi.com/u/trooper2)\
**Post date:** [July 7, 2014, 5:29pm UTC](https://forums.digi.com/t/mam-please-help-me-out-i-want-to-activate-external-i-o-in-two-rcm4000-so-as-to-transfer-data-from-one-module-to-other/13202/2 "2014-07-07T17:29:30Z")

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To use external IO you need to put the following at the top of your code:

#define PORTA\_AUX\_IO

If you want to use two boards as master and slave see samples\slaveport\*.c.