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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.

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127 views

RS232 Voltage Level Boosting

I have a piece of old instrument circa 1988 that uses +-12V in its serial port. According to the manual, DTR pin (Data Terminal Ready) must be held at +8V in order for the instrument to recognize that ...
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1answer
60 views

RS-232 to RS-485 transceiver

I'm new in communication protocols and ICs. I would like to know if it is possible to connect a RS-232 (TX, RX and GND) to a RS-485 (Vcc, A, B and GND). I only need a half-duplex communication. The ...
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2answers
25 views

Modbus RTU using SoftwareSerial

Im trying to control a temperature controller using Arduino MEGA over SoftwareSerial. Im using Modbus-Master-Slave-for-Arduino library and I tried to test using example code below. It gives only <...
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1answer
66 views

Connect to a serial output device with 12V power input with 5V USB-TO-UART

I have DG600F coin acceptor with 12V power input and serial port output CP2102 usb-uart bridge and FDTI TTL-232RG cabel as an alternative A PC and Macbook as alternative I need to connect DG600F to ...
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0answers
49 views

Manually aligning uart signal [duplicate]

I'm using a fast microcontroller (AT89LP52) with 22.1184Mhz crystal. I have calculated that I can toggle each port pin in a matter of nanoseconds (as opposed to microseconds on the AT89S52) I have ...
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1answer
69 views

How to identify 422 or 485 bus from the PCB

I have a very old CPU card, maybe 1980's. It has following chips on it and most probably these are used for communication with the rest of the system. SN55188 Quad Line Drivers SNJ55189 Quad Line ...
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3answers
103 views

Connecting 2 external PCBs with a 1m cable

I would like to connect 2 PCBs. On each PCB there is a MCU and each MCU is able to send and receive commands from the other one. Also, PCB1 should supply power to PCB2. The 2 PCBs are separated by ~...
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2answers
54 views

RS232 to ethernet over LAN

Can I connect an rs232 Ethernet converter to a switch and expect to receive a data on a php server listening to the of IP conversor? In windows I need to install drivers to create a virtual com, so I ...
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1answer
107 views

RS422 and RS485; full-duplex or half-duplex?

I have extensively used RS232 transceivers in many projects and have fairly good understanding of UART communication using RS232 transceivers. MAX232 and MAX3232. Now I have to build my understanding ...
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2answers
236 views

RS-232 to I2C communication [closed]

I'm trying to establish communication between two boards, one of which has an RS232 output and the other with an I2C input. I've looked for adapters online and the only ones I've found seem to be ...
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1answer
57 views

Comparing MAX3232 vs MAX232 for line length

Which parameter in the datasheets of the line drivers MAX3232 and MAX232 can tell about the maximum length of the line for their correct operation if all else is same for the two circuits, that is ...
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3answers
198 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 ...
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1answer
104 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: ...
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2answers
177 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 ...
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1answer
83 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 ...
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2answers
61 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 ...
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0answers
21 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-...
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3answers
157 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 ...
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1answer
69 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 ...
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1answer
119 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 ...
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1answer
80 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 ...
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2answers
134 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 ...
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2answers
67 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 ...
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1answer
128 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 ...
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0answers
104 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 ...
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0answers
56 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
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2answers
439 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
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1answer
212 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 ...
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1answer
95 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 ...
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2answers
674 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-...
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0answers
53 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 ...
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1answer
102 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
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3answers
675 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, ...
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1answer
134 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
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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 ...
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2answers
253 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
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2answers
97 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 ...
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3answers
760 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
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1answer
125 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 ...
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3answers
98 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
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1answer
242 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!
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4answers
6k 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
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2answers
8k 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?
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0answers
100 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 ...
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2answers
107 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 ...
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2answers
101 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 ...
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vote
1answer
249 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
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0answers
104 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
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1answer
143 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
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1answer
459 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 ...