RS232 TO TTL 3.3V CONVERTER / RS232 TTL CONVERTERS
INDUSTRIAL PORT-POWERED RS232 TO TTL 3.3V CONVERTER
The TTL33-232-1 is a compact, rugged, industrial-grade, port-powered RS232 to 3.3V TTL converter, which can be used to convert RS232 to 3.3V TTL/CMOS compatible levels and vice versa. This industrial RS232 to 3.3V TTL converter operates within a temperature range of -40ºF to 185ºF (-40ºC to 85ºC), and features 600W surge protection and 15kV ESD static protection. The unit is efficiently powered from the RS232 data line, and the full-duplex RS232 to full-duplex TTL conversion eliminates the need of auto-turnaround feature. This RS232 to TTL 3.3V converter also comes with the auto-sensing and self-adjusting features, which automatically adjust baud rate, parity, stop bit and other COM port parameters to the devices that it is connected to. Therefore, it requires no external power, manual settings or software drivers, making the unit a highly reliable and truly plug-and-play device for both commercial and industrial applications.
CommFront's product quality is ensured by our strict ISO 9001:2008 quality control system, and we back our high-quality RS232 to TTL converter with a 30-day risk-free money-back guarantee and a 5-year replacement warranty.
FEATURES (INDUSTRIAL RS232 TO TTL CONVERTER)
- Converts RS232 to 3.3V TTL and vice versa.
- Port-powered, no external power or RTS, DTR required.
- Industrial grade enclosed in a rugged, rustless ABS housing.
- 300 to 115.2K Baud operation (auto-sensing & self-adjusting).
- Operating temperature: -40ºF to 185ºF (-40ºC to 85ºC).
- Plug and play (hot-pluggable, data format auto-sensing & self-adjusting).
- No software drivers, flow control, DIP switch or jumper settings required.
- Built-in 600W surge protection, 15kV static protection and circuit protection.
- Surface Mount Technology manufactured to RoHS and ISO-9001 standards.
- Safety: Strictly certified by TUV (Cert No. SG-CE-090012).
- 5-year manufacturer's warranty.
SPECIFICATIONS (INDUSTRIAL RS232 TO 3.3V TTL CONVERTER)
| Part Number: | TTL33-232-1 |
| Compatibility: | EIA/TIA RS-232C standard and TTL 3.3V level |
| Power Source: | Port power from RS232 data line |
| Current Consumption: | Less than 10mA |
| Baud Rates: | 300 to 115,200bps (Auto-sensing & Self-adjusting) |
| Distance: | RS232 side: 16ft (5m); TTL side: 10ft (3m) |
| Connector: | RS232 Side: DB-9 Female; TTL Side: DB-9 Male; Termination Board: DB-9 Female and a 3-Way Terminal Block |
| Surge protection: | 600W |
| Static protection (ESD): | Up to 15KV |
| Dimensions (H x W x D): | 0.63 x 1.3 x 3.5 in (16 x 32 x 88 mm) (with Termination Board) |
| Weight: | 1.27 oz (36 g) (with Termination Board) |
| Operating Temperature: | -40ºF to 185ºF (-40ºC to 85ºC) |
| Operating Humidity: | Up to 90% RH (no condensation) |
TTL SIGNAL LEVELS
| TTL Input | TTL Output |
| High (>2.0V) | High (3.3V) |
| Low (<0.8V) | Low (0.0V) |
CONVERTER CONNECTOR / TERMINAL BLOCK PIN OUTS
RS232 Side (Female)
| Pin | 1 | 4 | 6 | 7 | 8 | 2 | 3 | 5 |
| Signal | DCD | DSR | DTR | CTS | RTS | TX | RX | GND |
| Function | Tied | Tied | TX | RX | GND | |||
Note: Some software requires handshake line acknowledgements. To satisfy the requirements, our converter's handshake lines are tied together (DCD, DTR, and DSR tied together, and RTS and CTS tied together). Therefore, you don't have to modify your existing software.
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| DB-9 Female (view from front) |
Terminal Block Side
| DB-9 Male Pin | 1 | 3 | 5 |
| Terminal Block | TX | RX | GND |
| Function | TTL Out | TTL In | GND |
Note: The TTL33-232-1 comes with a 3-way terminal block for easy wire connections. However, you may choose not to use the terminal block provided and simply follow the above table for pin assignments.
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| DB-9 Male (view from front) / Terminal Block |
CONNECTIONS

Figure 1: TTL33-232-1 Connection Diagram
TROUBLESHOOTING RS232 TTL 3.3V CONVERTER
Loopback Test

- Connect a TTL33-232-1 to your PC's COM port and short TX and RX on the TTL terminal block (as shown above).
- Run 232Analyzer FREE version software on your computer.
- Select "ASCII" for both the Send and Receive data formats. Then send command and/or string such as "CommFront" from the 232Analyzer software. You should receive an echo of the command/string sent ("CommFront"). By performing a simple loopback test like this, you can test both the transmitter and receiver of the converter. This is very helpful when you are in doubt about the performance of your converter.
232Analyzer is an advanced RS232 Serial Protocol Analyzer software that allows you to control, monitor and analyze serial port (RS232 / RS485 / RS422 / TTL, etc.) activities. Not just the data, it also allows you to monitor or change RS-232's line states: RTS, CTS, DTR, DSR, DCD, and RI.
The FREE version (no time limitation) can be downloaded from here.
TECH NOTES
RS-232: 3 easy steps to understand and control your RS232 devices
RS-485/RS422: Building a reliable RS485/RS422 network




























