yara, if you are skipping answers on key questions then how we could help you
I can assure you that in 7.20 the commands on all drivers, so also DNP3_TG and IEC850, are working fine. Were thoroughly tested by us and they are in use by many customers. So this is probably some configuration issue in your project, e.g. in Command Processing or maybe some unusual coincidence of conditions. We need more info as "it was working and in 7.20 does not work"

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If you don't like to answer questions on public, then please send to your local Support:
- description what are you using to trigger a command (screen element, set value function, command processing)
- description what happens when you are trying to send a command
- the project backup
- names of affected variables and name of screen
- best - using DiagViewer - turn on full logging for DNP3_TG /iec850 driver and attached to email also LOG-file (on Forum there are threads with more info how to do this).