# B3, com- and boot-error indication

In this example we want to create the following scenario:

* CH1 shall control a green lamp which is on when all is OK
* CH2 shall control a yellow lamp that signals warnings
* CH3 shall control a red lamp that signals alarms
* Additionally communication alarms shall be indicated also on CH3 with red lamp.

## Operation mode

To achieve this the relevant alarm groups must connected to their alarm/warning events in B3. Warnings must be directed to CH2 and alarms to CH3.

Depending on the monitoring system type correct operation mode must be selected as described in [Operation modes](/cg1018-relay-box-installation-manual/installation/config-file/url__3_different_modes.md).

## Channels logic configuration

In the config file, the following must be set:

```sh
TURN_ON_CH3_IF_CONNECTION_FAILS=1
INVERT_CH1=1 
INVERT_CH2=1
INVERT_CH3=1
```

We want to set CH1 as power output active when there is no alarms so it must be set to PS as there is already a logic negation in this channel. 

For CH2 and CH3, to compensate the software logic negation created, it is necessary to add hardware negation by changing jumpers for CH2 and CH3 to NPS as described in [Jumper settings for PS and NPS modes](/cg1018-relay-box-installation-manual/installation/hardware-configuration/ps-and-nps-modes/jumper-settings-for-ps-and-nps-modes.md).

Now, with the logic negation in CH1 and two negations in CH2 and CH3, the box will signal warnings on CH2 and alarms on CH3. 

CH1 will be active for no alarms. All channels will be active while CCG1018 boots, or fails to boot.

CH3 will be active in case of no contact with the server. 


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