# Data Sheet

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<table border="1" id="bkmrk-c20-c21-c22-c23-c24-" style="border-collapse: collapse; width: 100%;"><colgroup><col style="width: 50%;"></col><col style="width: 50%;"></col></colgroup><tbody><tr><td>**[![8687e11c-6546-4888-bb0e-5ec48c9a7daf.jpg](https://doc.redisage.com/uploads/images/gallery/2024-03/scaled-1680-/8687e11c-6546-4888-bb0e-5ec48c9a7daf.jpg)](https://doc.redisage.com/uploads/images/gallery/2024-03/8687e11c-6546-4888-bb0e-5ec48c9a7daf.jpg)**

</td><td>**Features**

- Ethernet converter to RS232/RS485
- ESD protection for the RS485 data line
- Power supply: +12 to +30 VDC
- Transmission speed up to 115200 bps
- Tx, Rx and power LED indicators
- RS485 embedded termination 120 ohm
- Operating temperatures: -40°C to +75°C
- DIN rail mounting
- Dimensions: 90x56.4x22.5 mm
- 3 years warranty
- Customization of OEM is welcomed

</td></tr></tbody></table>

### Introduction

C20 - C22 are a products family of reliable converters based on the **ESP32 Xtensa LX6** microcontroller, extending the capabilities of industrial devices.  
C23 - C25 are a products family of reliable converters based on the **STM32F4** microcontroller, extending the capabilities of industrial devices.

The addition of a network interface allows remote access and full control over communication via a computer.

The user performs the basic configuration of transmission parameters in a browser or via a Telnet/serial console.

Dedicated EMC integrated circuits guarantee improved connection quality by limiting the impact of the interferences typical for an industrial environment.

### {{@170#bkmrk-specifications}}

{{@170#bkmrk-redisage-pn-c20-c21-}}

### Variants  


#### C20 - Serial Port Server (2x RS232)

<div drawio-diagram="1517"><img src="https://doc.redisage.com/uploads/images/drawio/2025-09/drawing-29-1758197717.png" alt=""/></div>

#### C21 - Serial Port Server (1x RS485)

<div drawio-diagram="1519"><img src="https://doc.redisage.com/uploads/images/drawio/2025-09/drawing-29-1758197781.png" alt=""/></div>

#### C22 - Serial Port Server (2x RS232/RS485)  


<div drawio-diagram="1522"><img src="https://doc.redisage.com/uploads/images/drawio/2025-09/drawing-29-1758197935.png" alt=""/></div>

<p class="callout danger">\* In the C22 converter user should use only RS232 or only RS485 interface of one port as they occupy the same internal bus of the device. It means, you can't use ports: RS232-1 &amp; RS485-1 at the same time and RS232-2 &amp; RS485-2 at the same time!</p>

#### C23 - Serial Port Server (4x RS232)  


<div drawio-diagram="1523"><img src="https://doc.redisage.com/uploads/images/drawio/2025-09/drawing-29-1758197992.png" alt=""/></div>

#### C24 - Serial Port Server (4x RS485)  


<div drawio-diagram="1528"><img src="https://doc.redisage.com/uploads/images/drawio/2025-09/drawing-29-1758198320.png" alt=""/></div>

#### C25 - Serial Port Server (2x RS232 &amp; 2x RS485)  


<div drawio-diagram="1530"><img src="https://doc.redisage.com/uploads/images/drawio/2025-09/drawing-29-1758198457.png" alt=""/></div>

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### {{@170#bkmrk-pin-assignments}}

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### LED indicators

<table border="1" id="bkmrk-converters-c20---c22" style="width: 106.905%;"><colgroup><col style="width: 17.7592%;"></col><col style="width: 10.6079%;"></col><col style="width: 19.7855%;"></col><col style="width: 17.7592%;"></col><col style="width: 9.41597%;"></col><col style="width: 24.7914%;"></col></colgroup><thead><tr><td aria-sort="Brak" class="ak-renderer-tableHeader-sortable-column__wrapper align-center" colspan="3" data-colwidth="132,93,259">**Converters C20 - C22**

</td><td aria-sort="Brak" class="ak-renderer-tableHeader-sortable-column__wrapper align-center" colspan="3" data-colwidth="136,99,241">**Converters C23 - C25**

</td></tr></thead><tbody><tr><td colspan="3" data-colwidth="132,93,259">[![20708068-859a-46bf-8b76-783b7400789a.png](https://doc.redisage.com/uploads/images/gallery/2024-03/scaled-1680-/20708068-859a-46bf-8b76-783b7400789a.png)](https://doc.redisage.com/uploads/images/gallery/2024-03/20708068-859a-46bf-8b76-783b7400789a.png)</td><td colspan="3" data-colwidth="136,99,241">[![66a7b90e-9af7-4b47-ae63-40409f98a845.png](https://doc.redisage.com/uploads/images/gallery/2024-03/scaled-1680-/66a7b90e-9af7-4b47-ae63-40409f98a845.png)](https://doc.redisage.com/uploads/images/gallery/2024-03/66a7b90e-9af7-4b47-ae63-40409f98a845.png)</td></tr><tr><td class="align-center" data-colwidth="132">**LED indicator**

</td><td class="align-center" data-colwidth="93">**Color**

</td><td class="align-center" data-colwidth="259">**Function**

</td><td class="align-center" data-colwidth="136">**LED indicator**

</td><td class="align-center" data-colwidth="99">**Color**

</td><td class="align-center" data-colwidth="241">**Function**

</td></tr><tr><td data-colwidth="132">PW

</td><td data-colwidth="93">Blue

</td><td data-colwidth="259">Power

</td><td data-colwidth="136">PW

</td><td data-colwidth="99">Blue

</td><td data-colwidth="241">Power

</td></tr><tr><td data-colwidth="132">ETH

</td><td data-colwidth="93">Green

</td><td data-colwidth="259">Network activity

</td><td data-colwidth="136">ETH

</td><td data-colwidth="99">Green

</td><td data-colwidth="241">Network activity

</td></tr><tr><td data-colwidth="132" rowspan="2">ST

</td><td data-colwidth="93">Orange

</td><td data-colwidth="259">Console mode

</td><td data-colwidth="136">CN

</td><td data-colwidth="99">Yellow

</td><td data-colwidth="241">Console mode

</td></tr><tr><td data-colwidth="93">Red

</td><td data-colwidth="259">Service mode

</td><td data-colwidth="136">COM

</td><td data-colwidth="99">Green

</td><td data-colwidth="241">RS232/RS485 activity

</td></tr><tr><td colspan="3" data-colwidth="132,93,259" rowspan="2"></td><td data-colwidth="136">SR

</td><td data-colwidth="99">Red

</td><td data-colwidth="241">Service mode

</td></tr><tr><td data-colwidth="136">ER

</td><td data-colwidth="99">Yellow

</td><td data-colwidth="241">Error

</td></tr></tbody></table>

### {{@221#bkmrk-enclosure-dimensions-2}}

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### Getting started  


#### Power supply

Serial Port Servers C20 - C25 have wide voltage power input (12-30 VDC) and the power consumption is less than 1W.

#### Reset to factory defaults  


Reset to factory defaults is possible on the web page in the device section or using the service mode.


#### Service mode

##### {{@173#bkmrk-procedure-to-enter-s-2}}

{{@173#bkmrk-turn-off-the-power-o-1}}

##### {{@173#bkmrk-procedure-to-enter-s-3}}

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##### {{@170#bkmrk-list-of-commands-in-}}

{{@170#bkmrk-command-description--1}}

<p class="callout warning">{{@170#bkmrk-in-the-service-mode%2C}}</p>

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SR-D