- General Info
- Specifications
- Pinouts
- Images
- Troubleshooting
- Applications
DESCRIPTION
The TTL-232-33P is a bi-directional port powered RS232 to 3.3V TTL converter which converts a full-duplex RS232 port to a 3.3V TTL signal. A built-in data direction auto-turnaround feature automatically enables the TTL driver when data is present from the RS232 port, eliminating the need for software drivers, and making the device fully plug-and-play. The TTL-232-33P has a DB9 female connector on the RS232 serial port, and DB9 male connector on the TTL port. A separate terminal block is included with the product. The terminal blocks plugs into the TTL port, providing screw-lug wire terminations for the port. The unit is enclosed in a rugged ABS housing, and is powered from the RS232 data lines; no external power is required. This converter operates from 300 to 115,200 baud.
TTL VOLTAGE LEVELS
TTL INPUT | TTL OUTPUT |
HIGH (>2.0) | HIGH (3.3V) |
LOW (<0.8)< /td> | LOW (0.0V) |
FEATURES
- Plug-and-Play (Hot-pluggable)
- Port Powered - No External Power Needed
- Data Direction Auto-turnaround - No Flow Control is Necessary
- Built-in 600W Surge and 15KV Static Protection
- MTBF(Mean Time Before Failure): 252,948 Hours
- 5 Year Manufacturer's Warranty
- RoHS 3, CE, FCC and REACH Certified
PRODUCT COMPLIANCES

IN STOCK
30 Day Money Back Guarantee!
5 Year Replacement Warranty!
DATASHEETS
2D CAD DRAWINGS AND 3D MODELS
ISO 9001:2015 QUALITY MANAGEMENT

Our internationally recognized ISO 9001:2015 Quality Management System (Cert. No. 743003912) with a scope of Design, Sales, Distribution of Data Communication and IT Support Services was recognized and certified by TÜV Rheinland of North America known for its very demanding and stringent requirements. For more details see our Quality Policy.
COMMUNICATION | |
STANDARDS: | EIA/TIA RS-232C Standard |
BAUD RATES: | From 300 baud To 115,200 baud |
CONNECTOR TYPES: | RS-232 Side: DB9 Female and TTL Side: either DB9 Male or 5 Way Terminal Block |
DISTANCE: | RS-232 Side: 16 ft (5m) and TTL Side: up to 10 ft (3m) |
ELECTRICAL | |
POWER SOURCE: | Port Powered From RS-232 Data Lines |
CURRENT CONSUMPTION: | Less Than 10 mA |
STATIC PROTECTION: | 15KV Electric Static Discharge (ESD) Protection |
SURGE PROTECTION: | 600W Surge Protection |
MECHANICAL | |
HOUSING: | Rugged ABS |
WEIGHT: |
With Terminal Block:
1.2oz (36 grams) Without Terminal Block: 0.8oz (24 grams) |
DIMENSIONS: |
With Terminal Block:
3.16 X 1.32 X 0.73
in (80.3 X 33.4 X 18.6 mm) Without Terminal Block: 2.47 X 1.33 X 0.70 in (62.8 X 33.8 X 17.8 mm) |
ENVIRONMENTAL | |
OPERATING TEMP.: | -4ºF to 140ºF (-20ºC to 60ºC) |
STORAGE TEMP.: | -40ºF to 185ºF (-40ºC to 85ºC) |
OPERATING HUMIDITY: | 5% To 95% - No Condensation |
QUALITY | |
PRODUCT SAFETY: | CE, FCC and RoHS Conformance Certified |
QUALITY MANAGEMENT: | Manufactured and Distributed to ISO 9001:2015 QMS |
MEAN TIME BEFORE FAILURE: | 252,948 Hours |
RELIABILITY: | Low Failure Rate - 99+% Reliability Since Inception |
WARRANTY: | 5 Year Replacement Warranty |
RS232 Side DB9 Female
Signal | DCD | DTR | DSR | RTS | CTS | TX | RX | GND |
Pin # | 1 | 4 | 6 | 7 | 8 | 2 | 3 | 5 |
Function | TIED | TIED | TX | RX | GND |

3.3V TTL Side DB9 Male or Terminal Block
Signal | NC | TTL IN | TTL OUT | NC | GND |
Pin # | 1 | 2 | 3 | 4 | 5 |
Function | NC | TTL IN | TTL OUT | NC | GND |














Using one TTL-232-33P unit:
- Check that all connections comply with the connection diagrams.
- Perform a loop back test on one unit:
-
- Connect the IN to OUT on the TTL port.
- Connect the RS-232 port to the PC RS-232 port.
- Running a hyper terminal program on the PC, send ASCII characters to the TTL-232-33P converter from one PC port, and check that the characters are received at the same PC port. This tests that the transmit and receive functions of the TTL-232-33P unit is working properly.
Using two TTL-232-33P units:
- Check that all connections comply with the connection diagrams.
- Perform a loop back test on two units:
-
- Connect the two TTL ports.
- Connect the two RS-232 ports to two PC RS-232 ports.
- Running hyper terminal programs on both PCs, send ASCII characters to the TTL-232-33P converter from one PC port, and check that the characters are received at the 2nd PC port. Repeat the test in the opposite direction. This tests that the transmit and receive functions of both TTL-232-33P units are working properly.
Download FREE FULL VERSION AccessPort Advanced Serial Monitor, Simulation and Data Analysis Software Tool. This software tool is great for testing converters. Supports Windows 98/XP/VISTA/WIN 7/WIN 8/WIN 10. DOWNLOAD SOFTWARE AND USER MANUAL
Below are some of the RS232 to TTL converter applications.
