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title: "Configuring a P400 Radio in Serial Passthru Mode"
canonical: "https://farmconnect.docs.rubiconwater.com/space/FER/2063368193/Configuring%20a%20P400%20Radio%20in%20Serial%20Passthru%20Mode"
format: markdown
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Some radio types (P400) are required to be configured on a site-to-site basis. Different site may even require different radio firmware releases to connect to the existing networks. 

The Radio serial ‘passthru’ mode can be used to directly update and configure a radio using a Rubicon Programming Diagnostics Tool (USB->RS485->Radio)

> ℹ️ A standard PDT should not be used to supply power to the FerIT P400 to test the Radio communications. A PDT with external DC supply (powered PDT) or a battery must be used in this case.

# Requirements

| **Description** | **Qty** | **Detail** |
| --- | --- | --- |
| For p400 FIRMWARE updates  
The compatible version of ‘**ATFirmwareUpgrade**’ to match the firmware required | 1 | Contact Tech Services to obtain correct microhard P400 firmware for the site |
| for p400 CONFIG updates  
The latest version of ‘**MHXConfig**’<br>Alternative is to use TeraTerm, as described below | 1 | Contact Tech Services to obtain correct microhard configuration for the site |

#   
Setting Up

When ‘passthru’ mode is first enabled, the p400 radio will be in DATA mode. To validate a connection, put  
the radio into CONFIG or AT COMMAND mode. If a radio has previously been provisioned, a CONNECT XXXX message might appear, also confirming the connection.

  
All manual commands sent through the serial terminal should be sent with the serial port set up with the  
following configuration:  
• 9600 8N1  
• 0 ms delays

> ℹ️ NOTE: Remember to cycle the power to the FerIT Node when you are finished using passthru mode.

# Passthru Mode Control w/ P400

> ℹ️ NOTE: FerIT Firmware version must be v1.13.1 or higher.

1. Open up the YAT terminal window or other similar terminal tool.
2. Type** passthru** within 5 seconds after powering up FerIT.
3. Wait for a ‘**ready()**’ response.
4. A message should be received from the radio:   
'NO CARRIER'  
'OK'
5. The radio is now in CONFIG mode or AT COMMAND mode.
6. Send ‘**AT&V**’ and hit enter to validate current settings.

## Putting the radio in DATA mode

If the radio is already in CONFIG/AT COMMAND mode

1. Type ‘**ATA**’ and hit enter key
2. The radio should switch to DATA mode

# Performing FIRMWARE updates via passthru mode

> ℹ️ **Note**
> ℹ️ 
> ℹ️ Due to the 9600 baud limitation, requests from the AT Firmware Upgrade tool to change baud are ignored,

**A firmware update at 9600 baud takes around 10 minutes to complete.**

**Step 1**

If the radio is in CONFIG mode, put it back into DATA mode by sending the command ‘**ATA**’ through Teraterm

**Step 2**

DISCONNECT teraterm from the COM port:

**Step 3**

Open up the AT Firmware Upgrade application.

**Step 4**

Select the correct COM port as used in Teraterm.

**Step 5**

Click the elipses (…) and select the firmware to load to the radio.

**Step 6**

Ensure that the inter packet delay is not lower than 20ms. Passthru firmware upgrades have been tested with 20ms only, other rates may not have the desired effect.

**Step 7**

Click the **Load** button.

**Step 8**

Monitor the messages during firmware load. When the prompt appears ‘Continue in 9600 (slow) mode’, click **OK **to continue.

**Step 9**

Wait for the firmware load to complete.

**Step 10**

Put the radio back to config mode (by typing **+++**, cycle power and type *passthru*) and perform a '**AT&V**' query to validate the firmware successfully updated.

# Performing CONFIG updates via passthru mode

## With TeraTerm

### Serial Port Setup

It is important to CHANGE THE SERIAL SETTINGS before sending an at command file to the modem. If the settings are not changes to slow down transmission, the passthru will not be able to handle the speed of send and the RADIO MAY BE BRICKED. Make sure that the FerIT P400 is in CONFIG/AT COMMAND mode.

**Step 1**

Click on ‘Setup’->'Serial Port...'

**Step 2**

Set the port settings to 

- 9600 8N1
- 0ms character delay
- 500ms line delay

**Step 3**

Click **OK **to save the port settings.

### Sending the file

**Step 1**

Click on ‘File’->'Send File...'

**Step 2**

Select the .cfg file required.

**Step 3**

Make sure that the BINARY checkbox is NOT ticked.

**Step 4**

Click 'Open' to start the file send.

**Step 5**

If there is a RESET command in the cfg file, the radio will RESET. If this occurs, you will need to put the unit back to CONFIG mode to check the write was successful.

> ℹ️ The P400 configuration (radio) file should begin with ‘AT&Fx’ and ‘AT&W’ (where *x* corresponds to the region) to perform a factory reset of the FerIT P400 radio. This step is crucial for recovering the FerIT P400 nodes.

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