Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [rs232]

RS-232 is the electrical standard used on most serial ports. Note that this standard is a +/- 15 volt system and requires a FDMI converter to make it compatible with TTL logic levels.

0
votes
1answer
18 views

MAX232 Replacement

I have a circuit where a 12V square wave signal (a Profile Ignition Pickup signal from a Ford EDIS ignition module) was fed to an MCU via a MAX232 chip. My understanding of the MAX232 is that the ...
1
vote
1answer
33 views

How Schneider PowerLogic ION8650 and ION8600 meters interface with the LAN

A number of "Schneider PowerLogic ION8650 and ION8600 meters" and a "GPS NTP 100 time synchronization device" around 30 in number are there for measuring total energy injected to electrical grid ...
0
votes
1answer
89 views

Connector Identification on Instrument

I have a piece of instrument made around 2000 with a connector to computer that I cannot recognize. Can someone help me out? It is a 20-pin connector, with 10 pins on each row. Pictures are here: ...
4
votes
2answers
157 views

RS232 Unusual “Framing Error”

I have an old piece of instrument that suppose to connect with a Windows XP machine. I keep getting "Framing Error" messages on the instrument panel while the PC side shows that the instrument could ...
0
votes
1answer
74 views

Detect an unknown communication protocol and read data on it

We have old type textile machinery in our factory. (open end machine) on the machine's screen is showing the operating efficiency of the machine. Under the hood, When I follow the cables, the sensors ...
0
votes
2answers
59 views

What specs does the “gros condo” (big capacitor) needs to have?

I have a pair of Dynaudio Air 20 at home. Unfortunately, the cable that used to control the speakers via RS232 died. I opened the cable, and saw that it was a customized RS-232 to TTL adapter, but ...
0
votes
0answers
14 views

Logic leves and protocol, interfacing HP39GS to arduino Wemos D1

Im trying to connect HP39GS scientific calculator to Wemos D1 arduino. It has TTL RS-232 serial port. Pinout is somewhat: Vcc, TX, RX, GND. Looks like HP39GS protocol for serial port is not pure RS-...
0
votes
3answers
67 views

Transmission from atmega32 to PC using max232 not working

Transmission from atmega32 to PC using max232 not working. When I checked the data from the Tx pin (in the realterm software) of atmega32 it was fine. But there was no output data from max232, when I ...
0
votes
1answer
55 views

Protecting RS-232 from overvoltages

I am using Some arduinos (5V Pro-Mini, but planing to move to actual ATMEGA chip) over a distance of few metres. These are connected using standard Alarm cable (I had problems with Ethernet cable and ...
0
votes
1answer
111 views

How to monitor one wire “kind of” protocol

In the current network, there's 1 master device, which gathers data from over 20 devices. Nameplate says the baud rate is 2400. In the bus cable there's one data wire, 12V and GND. A friend of mine ...
0
votes
1answer
70 views

GSM Modem Transmission Issue

I'm having a problem getting this GSM modem to work with an FPGA (Spartan 3). I've already implemented UART transmission on the FPGA side,the MAX232 to convert TTL->RS232, and 3.3V->5V logic level ...
0
votes
2answers
116 views

RS485 vs RS232 similarity vs differences

I have used UART RS232 communication between MCUs extensively. Now I need to interface my STM32F407 MCU over RS485 bus with with devices. I have understood few things about RS485 but not-clear about ...
0
votes
2answers
55 views

MAX232 vs TRS202EC Line Drivers

I have used MAX232 as UART serial line driver using 5V power supply. Now I have come across TRS202 chip in a circuit. It also run with 5V power supply. Does this chip has some special difference or is ...
2
votes
1answer
107 views

RS-232 interface chip problem - why is the voltage level so wrong?

1. What I want to do: I have a PCB with an AVR microcontroller (ATmega16U4) on it. I want the microcontroller to communicate with my computer through an RS-232 cable. 2. What I did: I added an ...
0
votes
0answers
63 views

What is this weird behaviour I am observing with doing a loopback around MAX3232?

So this is my pretty little circuit that I made. AFAIK all connections are fine and I have tested them using multimeter for any shorts. I was actually testing the circuit by loop back shorting J1's ...
0
votes
0answers
52 views

Serial communication between raspberry and laptop not giving right values

I want to communicate between a Raspberry Pi 3 model B and a laptop using a USB to RS-232 cable and this RS-232 to 3.3V TTL converter via the serial module in Python: GND is connected to board pin #6 ...
4
votes
2answers
416 views

Can a MAX232 IC be used for RS-232C standard?

I have a GT01 Panasonic LCD which it's interface is RS-232C. I have read that the difference between RS-232 and RS-232C is their voltage level which it's ±5 V in RS232C. Can I use a MAX232 IC to ...
2
votes
1answer
176 views

Is there a standard describing the UART data frame protocol?

The "U" in "UART" stands for "Universal", but I'm having trouble finding any standard that describes the framing protocol that's used in UART; e.g. the start bit, stop bit, parity options, and baud ...
-1
votes
1answer
93 views

RS232 Data Format “Design” Questions (from non-EE) [closed]

I've been tasked with defining a format for (asynchronous) binary RS232 data sent from one device to another. These are mostly error messages and some engineering data from a custom autopilot device ...
-2
votes
2answers
423 views

What's the difference between a null modem cable and a gender changer? [closed]

Please ignore this question. It doesn't address the problem I was trying to solve (XY problem) and my edits have been reverted. Because it has answers, I can't delete it. It should be closed as off-...
0
votes
0answers
48 views

minimalist serial port addon to a basic 8052

Currently I have two microcontrollers connected to each other so that I have two serial ports. One to the PC and one to a wireless radio module. Now I'm considering replacing one microcontroller with ...
0
votes
1answer
82 views

Does this wiring pattern for a DB9 cable exist as a standard cable?

I have a scientific instrument that uses a DB9 cable to connect to the standard RS232 port on a computer for communication. I've deconstructed one of the cables as I needed to make another one but I ...
4
votes
3answers
616 views

Is the ATMEGA328P's serial baud rate quantised?

I'm using an ATMEGA328p, running from its internal oscillator (divided by 8 = 1MHz). I've (roughly) measured the oscillator output, using my Salae logic analyser, as ranging from 960KHz to 1000KHz, ...
0
votes
1answer
132 views

What is 8 pin tssop packed component?232/485 ethernet converter

-size = 2.9mmx3.1mm -GND pin = 1,6,7 connected -7.pin 4.7uh connected
8
votes
2answers
2k views

Why can't I successfully send messages over RS232?

So the past week I have been working on getting UART messages sent from a STM32F407 and reading it on my laptop through a ugreen RS232 to USB cable using termite. I have used STMCube to generate ...
6
votes
2answers
230 views

Purpose of this oscillator (74HCT14-based) on RS-232 to RS-485 converter?

I am reverse engineering an RS-232 to RS-485 converter to understand how it works. I have attached the schematic that I reverse-engineered from the PCB (apologies for the hand-drawn schematic). I've ...
0
votes
2answers
94 views

Help figuring out the interface on this bill validator?

I would like to interface this bill validator to a microcontroller (Arduino Mega). The website says it supports RS232,RS485,Optoisolated RS232 and USB interface. The one I have is currently intefaced ...
0
votes
3answers
557 views

How to find out whether serial standard is RS232 or TTL when stated as “serial(RS232/TTL)”

I am recently moving from C programming into automation engineering. I have learned about RS232 and TTL standards, and I understand that they are based on the same concept of serial communication, ...
0
votes
1answer
99 views

Intel Altera MAX 10 DEV KIT Interface - Can a RS232 6 pin PMOD module by Digilent be used seamlessly with MAX 10 for PC-FPGA UART communication?

I am planning to either purchase a MAX 10 or a DE2-115 dev kit to implement communication via both ethernet and RS-232. DE2-115 has both ports soldered onto the board, but MAX-10 has 2 ethernet ports ...
1
vote
3answers
95 views

Unsure how arduino is interpreting RS232 signal

Disclaimer: I am a novice. I have an RS232 connection with an RFID tag reader which I am monitoring via software on a desktop computer as well as an Arduino. The device is configured with 8E1 parity. ...
0
votes
1answer
199 views

What is the function of diode and capacitor in RS232 shifter circuit?

as shown in the picture, can anyone explain the capacitor and diode in detail? Thank you!
11
votes
4answers
5k views

What are TX and RX relative to?

I have been working with a device that uses RS232 communication to a PC. There has been some confusion as they have defined their TX and RX pins relative to the device. In their definitions they use ...
5
votes
2answers
6k views

What is the difference between RS-232 and RS-232-C?

I know about RS-232. Later, I heard about RS-232-C. Are these two standards the same or not? If not, what are the differences?
0
votes
0answers
86 views

RS-232 signals on Bluetooth modules like HC-06, HM-10, etc

I would like to access any I/O pins of a bluetooth module of the likes of HC-06, HM-10 or their clones from both a Windows PC and/or Android system connected wirelessly to the module. I need Windows ...
-1
votes
2answers
81 views

Hot switching between RS232 ports

I have a system with two serial devices (Arduino uControllers) connected to a single FTDI (USB-to-Serial) chip through a silicon switch. Each devices works fine on its own. I would like to be able ...
1
vote
2answers
100 views

FTD232RL displays gibberish

Hello there i am using dsPIC30F4013 and i have been trying to interface uart with pic. I want to send some data to PC via uart and display it on terminal, but what i get is far from what i expect, to ...
1
vote
1answer
194 views

max232 charge pump problem

I have a problem with my MAX232 chip and can't find the solution. The schematic of the chip is in the attachment. The chip is soldered on to a PCB. I've checked all the connections, the supply ...
0
votes
0answers
79 views

How to wire RJ12 to db9f modular adaptor?

I have a RJ-12 to DB9f modular adapter. There are 6 wires that come out of the adaptor (White, Black, Red, Green, Yellow Blue) - these, as I gather from pin out diagrams, correspond to the 6 jacks of ...
0
votes
1answer
109 views

Which cable for 230.4 Kbps RS-232

I have to communicate between a sensor module and micro-controller board. The sensor module uses UART at 230400 bps. I have used a MAX3227 on sensor module as well as micro-controller board. So, the ...
0
votes
1answer
382 views

How to connect STM32 with DAC?

I have to do a project for my Uni, where one of the requirements is to connect DAC (AD5721 - Datasheet) with STM32F405RGT6 (Datasheet - package : LQFP64). This is what I have so far (DAC connected ...
0
votes
2answers
66 views

RS232 Bridge cable stopping after some time

Im trying to reverse engineer a very old DOS program that connects with a machine using RS232, for this i setup a typical in the middle connection like this: From Computer A to PC A connection im ...
1
vote
1answer
610 views

USB to RS232 without host (slave devices)

I'm trying to get two slave devices (ie no host controller) to communicate. Slave 1: USB with FT232RQ chip Slave 2: DB9 Using standard USB to RS232 converter cables, I cannot get the two devices to ...
0
votes
0answers
81 views

Why, for RS232 DB25 and DB9 the TX and RX reversed?

Why, for RS232 DB25 and DB9 the TX and RX reversed? For example for a DCE, DB25 connector, TX is on pin 2 and RX on pin 3. However for DCE, DB9 connector, TX is on pin 3 and RX on pin 2. I thought ...
1
vote
1answer
1k views

FTDI USB/TTL-serial converter - what are TXD, TXL, RXD and RXL?

I've got a couple of TTL USB/serial converters. I think they're FTDI chips. As well as pins marked TX and RX, there are unpopulated holes marked TXD, TXL, RXD and RXL. I've previously thought that ...
0
votes
2answers
757 views

Is it possible to talk with Attiny85 via serial interface?

Alright, I know this question is pretty silly, but I have stumbled upon different posts saying opposing things. So to make a conclusion, does anyone knows for sure if it's possible to send data via ...
1
vote
1answer
171 views

Transmitting through IRDA as if its a native serial port. Possible?

I'm currently making a lazertag project that utilizes the standard UART data format for data I/O. Before I go make up another circuit board that connects a photo-transistor that senses a laser beam ...
0
votes
1answer
183 views

Can you send RS232 messages to yourself in PuTTY?

Say you use PuTTY serial mode and a USB to RS232 cable. Can you send messages to yourself if you wire the TX of the cable back to its RX, not haphazardly, there's probably a bit more set up detail. I'...
0
votes
2answers
198 views

Upon setting up serial UART between two boards I can only monitor send or receive, not both, Why?

I have an atmega389B talking to a SAMD21 chip over UART and am trying to monitor the data sent by the SAMD21 and 389B chip. The baud rate used to be 9600 8N1 and I was able to observe both the sent ...
0
votes
1answer
60 views

How can I confirm the correct pinout of a USB <> RS232 null modem cable?

A loopback test with HyperTerminal, or something similar, will confirm the cable itself is working. But I want to know if the pinout configuration is indeed as expected... i.e. That pins 2 and 3 are ...
-1
votes
1answer
84 views

Why all the other ultrasonic sensors are getting triggered when only one so actually triggered?

I have an ultrasonic sensor, HC SR04, connected to the atmega 8 controller along with an LED for the indication purpose. Let me discribe about my project with some anology. Say I have 20 rooms( ...