RS232 to TTL Converter Explained

This page explains the differences between RS232 to TTL converters and TTL to RS232 converters.

Figure-1: RS232 to TTL converter

Figure-1 shows a simple RS232 to TTL converter. It transforms RS232 signal levels into TTL signal levels. Let’s explore the pin descriptions and signal designations for both sides.

RS232 Side Pin Descriptions

The following table (Table-1) outlines the pin descriptions and signal designations for the RS232 side of the converter:

| RS232 Pin Descriptions | | ---------------------- | -------------------- | | 2 (RXD) | Receive Data input | | 3 (TXD) | Transmit Data output | | 7 (RTS) | Request to Send | | 8 (CTS) | Clear to Send |

Table-1: RS232 Side Pins

TTL Side Pin Descriptions

The following table (Table-2) outlines the pin descriptions and signal designations for the TTL side of the converter:

| TTL Pin Descriptions | | -------------------- | ----------------- | | TXD | 3 (Output) | | RXD | 2 (Input) | | RTS | 7 (Output) | | CTS | 8 (Input) | | GND | 5 (Signal Ground) |

Table-2: TTL Side Pins

TTL to RS232 Converter

The TTL to RS232 converter performs the opposite function of the RS232 to TTL converter. It translates TTL signal levels into RS232 signal levels. You can often use the same cable mentioned earlier, provided it has the correct mating connectors.

Logic Level Differences

It’s important to understand the differences in logic level representation between TTL and RS232. The following table summarizes these differences: