GREENCONNECT Russia – manufacturer of link, modem and NULL modem cable COM port DB 9 RS -232.

In St. Petersburg, since 2016, production of cast modem cable female-to-female and cable extension cable COM mother-father for the modem made it possible to significantly expand the range and the lineup manufactured products.

Usage modem or null modem cables for device control Cisco or game consoles, terminals, cash registers, various control devices, modems require both standard and special wiring.

GREENCONNECT produces null modem And modem cable COM port RS-232 both with standard wiring and according to special, individual schemes. For standard wiring diagram modem null The cable uses a nine-conductor cable. IN modem cable GCR-DB9CM2M also uses all 9 pr vodnikov.

High quality, shielded, stranded, soft, copper conductor allows the use GCR modem cable both for domestic and industrial purposes. Factory production modem cable guarantees its performance for a long time, thanks to internal fixation using Injection Molding technology.

Modem cable COM port models GCR-DB9CM2M are produced in lengths from 50 cm to 10 meters, as well as extension cord male-female COM port model GCR-DB9CM2F.

Partnership directly with the Russian manufacturer GREENCONNECT Russia will allow you to save significant money and use high-quality modem cable for your tasks.

You can order or buy a null modem cable from the warehouse in any quantity at the best price.

Please note that the wiring of the RS232 modem cable is varied (depending on the technical tasks).

Wiring diagram semiduplex RS-232 cable

This circuit is used to control 2 devices that send data to the floorduplex. For example, one device is sending data and both other devices are waiting for incoming data.At half duplex, both devices cannot transmit at the same time. If this happened, the data would be impossible to read. This method is used in all connection schemesfrom the main device to the receiving device. In this method, the computer (P3) cannot send data and interfere with the communication between external devices.

Wiring diagram duplex RS-232 cable

This cable is used when you need to control data exchange between two external devices that can transfer data async (full duplex mode). You need 2 RS232 ports on your computer (separate port for communication and incoming data). A modern Serial Port Monitor can display both sides of a complete dual RS232 communication in "Dual Ports" mode. In this method, the computer (P3, P4) cannot send data and interfere with the communication between external devices.

Problems when flashing receivers. Lack of COM port. Using a laptop

Most “old” computers and laptops purchased more than 5 years ago always had several COM ports (RS-232). At least there was always at least one “RS-232” connector.

Rice. 1. Connector on the computer case

Various external equipment was connected to it: mice, printers, modems, specialized equipment. Therefore, there were no problems connecting the receiver to the computer for firmware. It was enough to just connect, run the program to update the receiver’s software and calmly do everything necessary.

In modern computers, the RS-232 connector is often missing. This is where problems arise, often very unpleasant ones. In most receivers there are no other methods of “firmware” other than using “RS-232”. And not all receivers have a “USB” input for connecting an external flash drive.

And sometimes there is another problem: the laptop has a “COM” port, but it works with receivers of one model, but not with others. This is due to the laptop manufacturer's violation of the RS-232 data transfer standard. They do this in order to save charge energy. battery. If the receiver manufacturer was technically scrupulous and precise, then a special chip for the “COM” port will be installed in the receiver. Thanks to this chip, the receiver will work with both a laptop and a computer. But installing a microcircuit increases the overall cost of the product, and lately manufacturers have been saving even on these little things! This is why the problem of incompatibility between laptops and most receivers arises.

When using a computer, the problem of the lack of necessary “RS-232” ports is solved simply: you need to purchase an additional module with “COM” ports. This board installed in a computer is called “PIC-COM” or simply “COM ports board”.

Rice. 2. PCI card for a computer with two “COM” ports

If you are not good with computers and have never dealt with installing additional equipment into a computer before, then contact a specialist! Otherwise, you can “kill” expensive equipment.

After installing the board into the computer, the operating system “Windows” - “OS” assigns new installed ports number, for example, “1”, “2”… “25”.

When using a laptop, you cannot install a regular computer board: the standard and size are wrong. There are two ways to solve this problem: expensive, but high-quality, and cheap, but not fully compatible. In the first case, you need to purchase a special board with ports for the laptop. The price of these boards is high, and I was not able to purchase this board, even on order.

Rice. 3. Laptop board with “COM” port

And there’s a catch: “old” and “new” laptops have two different standards for additional equipment! Before purchasing, check the instructions for your laptop!

If you could not purchase a board for a computer or laptop, then there is only one option left: “USB”. Almost all modern computer models have a “USB” output, at least two, or even all eight! There are various USB to COM converters available for sale.

Rice. 4. “USB - COM” converter

Rice. 5. “USB - COM” converter circuit

How to solder a USB-COM adapter yourself. Option 1

How to make your own USB-COM adapter, which can be used to connect converters and other devices to computers that do not have a “hard” COM port.
Attention!
The adapter described below provides matching only RX and TX signals.
All other modem signals are not used.
For most devices running without hardware flow control, this is more than enough.
The adapter works 100% with Pilot VAF/MAF converters

Go!

For assembly you will need the following parts:

1. PL2303HX (USB-USART bridge from Prolific) - 1 pc.
2. MAX232CSE (UART-RS232) - 1 pc.
3. Quartz 12.00 MHz - 1 piece.
4. Capacitors 10 nF (smd1206) - 2 pcs.
5. Capacitors 1 uF (smd1206) - 6 pcs.
6. Resistors 27 Ohm (smd1206) - 2 pcs.
7. Resistors 1.5KOhm (smd1206) - 1 pc.
8. Mini-USB connector - 1 pc.
9. DB-9 male connector – 1 pc.
10. Foil PCB for board 48*22mm – 1 piece

Adapter diagram

Printed circuit board

Scheme files and seals in the format Eagle PCB Editor can be downloaded from this link

Assembly and configuration
Here, in fact, everything is elementary - we make a board, drill 4 holes and solder all the parts.
As a result, you should end up with an adapter like this:

To prevent the board from oxidizing, you can paint it with polyurethane varnish or any quick-drying car varnish that you have on hand.
Next, we connect this device to the port Computer USB.
Windows will detect the new device and ask for drivers

We go to the prolific website and download the most latest version firewood

At the time of writing, the latest driver was this one.

After feeding the Windows driver, the system should appear new COM Prolific port:

Now you need to check the functionality of the adapter

To do this, on the adapter in the COM port connector, use a screwdriver or a wire to connect contacts 2 and 3 (there are usually numbers stamped on the connector itself with the contact numbers - take a closer look) Alternatively, you can solder a temporary jumper:

Next, launch the “Hyperterminal” program (Start->Programs->Accessories->Communication->Hyperterminal)
There is no hyperterminal on Vista and Seven! Therefore, you will have to go to Google/Yandex to download hyperterminal or any equivalent.

Select our new com port in the connection settings:

Now we start the connection, select English layout and try to print something.

The symbols of the keys you press should appear on the screen:

If the letters do not appear, check the installation

That's all!
Now all that remains is to remove the jumper from contacts 2-3 and you can use the adapter for its intended purpose.

Those. The input of such a “converter” is connected to the free “USB” connector of the laptop, the driver (control program) is installed from the disk included in the kit, and system settings a virtual COM port appears with an assigned serial number.

How to solder a USB-COM adapter yourself. Option - 2

Picture 1.General form

The proposed unit in assembled form allows you to implement the principle: buy - connect. The device will allow users of personal computers to connect devices operating from a COM port (RS232C) to the USB port.

Approximate retail price: 540 rub.

The adapter will be useful in practical applications: for connecting to a personal computer various devices, as well as modems and programmers.

Specifications

Supply voltage from USB port: 5 V.

Current consumption: 20 mA.

RS232C connection speed: 110-230000 bps

Interface: USB1.1, USB2.0.

Supported operating systems: Win98, Win2000, WinXP, Vista, Linux, etc.

Overall dimensions of the device: 60x30 mm.

Contents of delivery

Adapter block assembly: 1.

Instructions: 1.

Design

Structurally, the adapter is made on a double-sided printed circuit board made of foil fiberglass, protected by a transparent heat-shrinkable tube.

The adapter provides all modem signals: DSR, DTR, RTS, CTS, RI, DCD, as well as the main signals RXD and TXD.

Figure 2. Electrical circuit diagram

Figure 3. View printed circuit board from the details side

Description of the block operation

Fundamental electrical diagram shown on pic 2.

The central part of the device is the CP2102 microcontroller manufactured by SILICON LABORATORIES. The MAX3243 converter manufactured by Texas Instruments is used as a level driver chip. The adapter provides all modem signals: DSR, DTR, RTS, CTS, RI, DCD, as well as the main signals RXD and TXD.

Installing the device in the OS

To install drivers for your computer, you must first download the driver that matches your operating system.

Next, install the driver on your Personal Computer. Connect the adapter. operating system will detect it and “ask” for the driver, you should indicate to it the location of this driver (the place where it was unpacked).

After successful installation, the LED on the adapter should light up, indicating that the device is ready for operation!

NEW Updated driver dated January 25, 2011

1. Driver for Win Vista You can download

2. Driver for Windows 2000/XP/Server 2003/Vista (v5.0) You can download

3. Driver for Linux You can download

4. Driver for Win98SE You can download

5. Driver for OS Mac You can download

6. an144sw.zip- Using this program you can change the ID codes of the USB-COM adapter. This is necessary in order to be able to use several 8050 on one PC. Use only for experienced users! You can download

CHECKING BM8050 OPERATION WITHOUT EXTERNAL EQUIPMENT

To check the transmission and reception of all necessary modem signals according to the connection of the COM device.

Install jumpers on pins 2-3, 4-6, 7-8 of the VM8050 COM connector.

Connect the device to the USB port of your PC.

See which port the OS has allocated for the device, to do this, go to Start ---Setting --- Panel Management --- System --- Equipment --- Dispatcher Devices ---Ports(COM and LPT) --- Silicon Labs CP210x USB to UART Bridge (COM1).

Run standard application HiperTerminal for Windows from Start --- Programs ---Standard --- Connection--- HiperTerminal.

Stop a running connection, if it is active, by clicking Call --- Stop at the top.

See which port is used by the program to communicate with the device, to do this, enter File at the top left --- Properties and opposite “Connect via” select the same port as in Device Manager (in our case COM1).

In the same window, make sure that “Hardware” flow control is selected in the program, to do this, click the “Configure” button in the center and select “Hardware” in the lower “Flow Control” window.

Exit the program settings by clicking OK and OK again.

Type the text "Text" in the HiperTerminal program, and the text "Text" is printed on the screen, which confirms that the device is working.

Remove jumpers from pins 2-3, 4-6, 7-8 COM connector VM8050.

Type the text "Text" in the HiperTerminal program, while there is no printing on the screen, which confirms that the device is working.

Setting up the driver and selecting a port for the USB-COM adapter

Here the first problems await us: firstly, the OS could assign a too large number to the virtual port, for example, “25”. And the program for flashing the receiver allows you to work with port numbers from one to four. Secondly, not all USB-COM converters can work with the firmware program and the receiver itself. The reason is that equipment manufacturers have designed their products and programs for them differently. All converters must be checked individually for your program and your receiver. It often happens that the converter works with some equipment, but not with others.

If the first problem is resolved by changing the port number in the OS settings, then the compatibility problem of the hardware, program and converter cannot be resolved.

To change the number assigned to the OS, you must change it manually. To do this, you need to enter the “Device Manager”: “Start” - “Settings” - “Control Panel” - “System”.

Rice. 15.6. "Control Panel"

In the window that appears, select the “Hardware” tab and click on the “Device Manager” button. The Device Manager window will open. In the window that appears, in the tree list, select the line “Ports (COM and LPT). In the drop-down list you will see all the ports available on your computer. Select your virtual port: “USB - COM converter”. I have a Prolific model converter.

Rice. 15.7. List of available ports

Click on this line with the RIGHT mouse button, in the window that opens, select the “Properties” building.

Rice. 15.8. Configuring the selected port

In the window that appears, select the “Port Settings” tab. In the “Speed” line, select “115200”, then click on the “Advanced” button.

Rice. 15.9. Configuring Port Settings

At the bottom of the window that opens, find the “COM Port Number” tab.

Rice. 16. Changing the COM port number

Click on the tab and select required number COM port.

Please note that some port numbers may be occupied by existing hardware, such as a built-in modem. You cannot use one port at a time!

After completing the settings, click “OK” to save the changes made and completely exit the settings mode, closing everything previously open windows. After this, restart your computer to make the necessary changes. If you changed the “COM” number of the “USB - COM” port of the converter, then simply unplug it from the computer connector and reconnect it.

Ready-made solutions for USB-COM adapters from manufacturers.

Adapter cable COM 9/25M -> USB AM 1m

Price - 300 rub.
Description Cable for connecting devices with serial interface(RS-232) to the USB port.
Cable or adapter connectors COM25M, COM9M, USB A
Compatibility
USB 1.1/2.0 compatible
Support Windows 2000, Windows XP
Other
Cable length 1 meter
Logistics
Package dimensions (measured in NICS) 21.5 x 14.5 x 4.1 cm
Gross weight (measured in NICS) 0.136 kg

TRENDnet adapter cable COM9M-->USB AM 0.6m

Price - 500 rub.
Basic
Manufacturer TRENDnet
Model TU-S9
Equipment type Adapter cable
Diameter 28/24 AWG
Performance Options
Data transfer rate 500 Kbps
Powered by USB port
Power consumption 500 mA - maximum
Compatibility
System requirements RAM 64 MB
OS support Windows ME, Windows 2000, Windows XP
Other
RoHS Compliant
Cable length 0.6 meters
Weight 75 grams
Working temperature 0 ~ 40°C

Package dimensions (measured in NICS) 23 x 16.8 x 4.6 cm
Gross weight (measured in NICS) 0.135 kg
External sources of information
Link to the manufacturer's website www.trendnet.com

Adapter - USB-COM adapter (RS-232)

Price - 1500 rub.
The adapter is designed for using devices and adapters designed to be switched on via a Com (RS232) port, for example, this is very important when using modern computers that only have USB, in this case, with this adapter you can use modern computers and laptops together with our devices and adapters, such as BMW Scanner, Mercedes Scanner, Scanmatik, etc.

Equipment for car services, car diagnostics, diagnostic equipment, car diagnostics, car scanner, car scanner, diagnostic station, chip tuning, car diagnostic equipment Carbrain, UNISCAN, ADP-504, KKL-USB, KKL-COM, BMW scanner, Opel scanner, BMW 1.3 .6, Automan, Opel scanner, BMW scanner, engine tester, gas analyzer, engine diagnostics, instrument panel diagnostics Transponder programmer, OBD-2, OBD2, odometer correction, U-581, engine starting, crash data, crash date, crash date, speedometer, tachometer.

Although you may need to use a null modem cable (2-3, 3-2, 5-5) and an adapter like -

Add to adapter USB extension cable Here's a straight null modem cable.

• Retail price 100r.
• Type A-A
• Length: 1.5 m

But for other resources you need " flipped over" null modem cable.

• Retail price 155.00 rub.
• Connector type: DB9 F - DB9 F
• Length: 1.8 m

or this adapter:

STLab U-350 (RTL) Adapter COM 9M -> USB AM

Price - 350 rub.
Basic
Manufacturer St-Lab
Model USB DONGLE SERIAL 1 PORT
Description The adapter allows you to connect a device with an RS-232 interface (for example, a modem) to the USB port of a computer.
Equipment type Adapter cable
Cable or adapter connectors COM9M, USB A
Built-in USB connector Yes
Performance Options
Data transfer rate 115200 bps
USB 1.1 interface
Powered by USB port
Support for Windows 2000, Windows ME, Windows XP, Windows Vista, Windows 2003 Server
Package dimensions (measured in NICS) 17 x 13 x 3.2 cm
Gross weight (measured in NICS) 0.077 kg
External sources of information Link to the manufacturer's website

About RS-232 (unsoldering of cables, connectors, brief description)

RS-232C contacts

Wiring out the “modem” cable for the RS-232C interface

Communication and RS-232 interface

Troubleshooting RS-232 Communications

RS-232C contacts

Contacts of the DB-9 connector of the RS-232C interface

Wiring out the “modem” cable for the RS-232C interface

Wiring out a "null modem" cable for the RS-232C interface

RS-232C cable wiring for Kramer switches

Communication and RS-232 interface

When working in potentially noisy environments, we need reliable means of transmitting data. The most common standard is still the archaic RS-232C (Recommended Standard 232 Version C), adopted by the EIA (Electronic Industries Association) in August 1969.
Advantages of RS-232:
Popular - all PC computers (but not Macs) are equipped with at least one RS-232 port
Ease of purchasing ready-made cables
Possibility of using hardware control of the transfer process (often not used!)
Disadvantages of RS-232:
Point-to-point communications (DTE? DCE)
Low speed by modern standards (usually 9600 baud [bits per second])
Works only at short distances (up to 10 m)
The composition of the communication lines between DTE and DCE devices is not precisely defined. The standard describes the functions of up to 25 trunk lines, but does not specify whether a particular line should or should not be used. Things are better (technologically) in the RS-422 standard. According to this standard, communication is carried out over two pairs of wires, and the transmitted signal can be received by more than one device. The RS-485 (Enhanced RS-422) standard uses a single pair of wires that is used for transmission or reception by many devices.
RS-422/RS-485 Features and Benefits:
Can be used for multipoint connections
Is the de facto standard for much of the broadcast video industry!
Can be used at distances up to 1.2 km
High noise immunity due to the use of differential (balanced) communication lines
Communication line extender KRAMER VP-43 Range Extender:
Designed to overcome the distance limitations of our RS-232 controlled products.
Converts to the RS-422 interface, and then back to RS-232, which allows you to use two pairs of wires as a physical medium.
Can be used to extend communication distance for any RS-232 null modem connection.
Can also be used to control our products via RS-422, or as a converter general purpose from RS-232 to RS-422 and back.
KRAMER VP-14 Port Extender:
Designed to overcome the limitation of the RS-232 interface, which can only make point-to-point connections. Allows communication between multiple devices with RS-232 interfaces.
Data that arrives at any of the device ports is forwarded to the other 3 ports.
Can be used to control the switch from 3 DTE devices (eg computers).
Works in all communication modes (number of bits, speed, parity, etc.) and does not require configuration of these parameters.

Troubleshooting RS-232 Communications

The following steps may help resolve problems encountered when communicating with Kramer devices via the RS-232 interface.
1. Make sure that a null modem connection is established between the device (switch, router) and the control computer (PC).
The easiest way (when using a 25-pin port on a PC) is to use the null modem adapter included with the device. Connect such an adapter with a 25-pin connector to the serial port of the PC, then use a straight cable - that is, with one-to-one wiring - connect the 9-pin connector of the adapter to the serial port on the device. (If the adapter is used with a partial cable, a minimum of 9-pin connectors must be connected at both ends: pin 2 to pin 2, 3 to 3, and 5 to 5.)
When directly connecting the 25-pin port on the PC to the 9-pin connector on the device (i.e. without a null modem adapter), connect the following:
Pin 2 on a 25-pin connector - with pin 2 on a 9-pin connector
Pin 3 on a 25-pin connector - with pin 3 on a 9-pin connector
Pin 7 on a 25-pin connector - with pin 5 on a 9-pin connector
Short together pins 6 and 20 on the 25-pin connector
Short pins 4, 5 and 8 together on the 25-pin connector
When directly connecting the 9-pin port on the PC to the 9-pin connector on the device, connect the following:
Pin 2 on the PC connector - with pin 3 on the device connector
Pin 3 on the PC connector - with pin 2 on the device connector
Pin 5 on the PC connector - with pin 5 on the device connector
Short together pins 4 and 6 on the PC connector
Short together pins 1, 7 and 8 on the PC connector
2. Make sure that all DIP switches on the device are set correctly.
3. Make sure that the settings for the data transfer speed on the PC and on the device match, and the correct com port is selected on the PC.
4. If multiple devices are being used at the same time, make sure they are all turned on. If any of the devices are turned off in a master/slave system, communication in such a system will not be reliable.
5. If your device has a “DISABLE TXD” feature, make sure this feature is turned off; Likewise, if a DIP switch is used to “disable reply”, ensure that reply is enabled.
6. Pin 3 on the RS-232 connector of the device is used to send data to the PC (this is TXD of the device and RXD to the PC). Pin 2 on the device connector is used to receive data from the PC (these are RXD devices and TXD on the PC). It may be useful to use a digital storage oscilloscope to verify that the device is transmitting/receiving data on the specified pins.
7. Most devices use a “bidirectional” communication protocol. This means that the same code is used both to send a command to the device to perform a certain action, and as a response from the device (in the PC) when you press a button on its front panel to perform a similar action. For example, if the user pressed the buttons and switched input 4 to output 5, the device sends the hexadecimal code 7B to the computer; at the same time, when the device receives code 7B, it will also work out the connection of input 4 to output 5. For such a protocol, it may be useful to analyze the codes sent by the device when pressing the buttons on its front panel in order to understand the communication protocol.
8. When troubleshooting, it may be helpful to use a communications program like Procomm or Viewcom to first analyze the codes the device is sending. Then you can try sending such codes back (see point 7), checking that the device responds to them correctly. Finally, you can send a code that will return the device to its state.
9. If a user-written program is to be used, if possible, first use proprietary program Make sure the connection between the PC and the device is working properly.
10. For equipment where RS-232 control is an option and is enabled by installing an additional hardware board, ensure that the board is installed correctly (as described in the manual). In particular, for the X02 series of switches, check the straight cable connected to the module and make sure that there are no jammed pins on the connectors.
11. Some devices may receive control from other pieces of equipment and may be configured to operate via RS-232 with that equipment rather than with a computer. In this case, you must configure the device correctly. For example, models BC-2216 and BC-2616 (matrix switchers sound signals 16X16) are configured at the factory (default) to work with the BC-2516 (16X16 video matrix switcher). In this case, the sound matrix receives control from the PC through the video matrix. If the sound matrix is ​​to be controlled independently, it should be reconfigured accordingly (to operate as an audio-only switching device).
12. If you need to send several commands, then before sending additional command you should make sure that the device has processed the previous command. To do this, wait until the previous command receives a response before sending the next one.
13. Make sure that you are using a real RS-232 interface to communicate with the device! Some equipment (such as the standard Macintosh serial port), although similar to RS-232, uses different communication modes.
14. When using a PC with the Windows NT4.0 (or lower) operating system, additional measures should be taken. This system is not plug and play and therefore setting up the computer ports on it is not an easy task. Please refer to your Windows NT documentation! Even if your program is running on a computer with a different operating system, it is possible that under Windows NT the port will not initialize correctly.
15. Please note that the operating distance for RS-232 (by definition) does not exceed 10 meters! If longer communication length is required, our VP-43 "Link Extender" should be used.
16. By definition, the RS-232 interface is intended for communication between 2 ports (in our case, a PC and a switch). If you need to connect together several devices with RS-232 interfaces, you can use VP-14 (for example, if the switch needs to be controlled from 2 computers and a BC-2000 controller).
(NOTE: Some of our products allow you to control multiple units in a daisy chain with straight cables - which doesn't seem right in light of the above! In fact, we configure the units in master/slave modes, with Only one device, the master device, is connected to the computer via RS-232. With this connection, the master device transmits information to and from the PC to the slave devices, and the ports are connected in pairs by the RS-232 interface.)

Installing new software into the satellite receiver is only possible via a null modem cable. In simple terms it is called firmware satellite receiver. For receivers equipped with an RS-232 connector, updating software, keys, taking a dump, restoring the functionality of the receiver in most cases is only possible using a null modem cable. To connect the receiver you will need a computer or laptop with a (USB-COM adapter) or a COM port. The operating system for matching the computer receiver can be Windows 98, Windows XP, Windows 7. Attention! Connect and disconnect the cable from the receiver only when it is disconnected from the 220 volt network. During a firmware update, never interrupt the software update process. All this can lead to failure of the satellite receiver.

Briefly about the null modem cable. The scheme is simple, and based on the photographs below it will not be difficult to make it yourself at home. As a last resort, he will buy it at the radio market or in a computer store. To make a null modem cable with your own hands, you will need 2 RS-232 connectors (female connector type), a cable with three cores and a screen, it is very important that it is shielded, which will give stability when working with it. Don't do it too long either! All this will need to be soldered according to the diagram below, guided by the photo, see below.

Diagram of a null modem cable for a satellite receiver

General view of a null modem cable. The total length can be up to 10 meters. It is recommended to use shielded 3-wire wire. Solder the screen to the ground.

photo 1

Below in the photo is a null modem cable for a satellite receiver without connectors. 3 wires and a screen are involved.

photo 2

Schematic representation of a null modem cable for the receiver.

photo 3

A modern laptop or netbook does not have an RS-232 port. Only USB 2.0 or USB 3.0 Therefore, to flash the satellite receiver firmware, you need to use a USB-RS232 adapter (see photo below). This adapter can be purchased at a computer store. It's inexpensive. The adapter comes with a disc containing software- driver. The driver must be installed on a laptop or netbook. Please note that the USB-RS232 adapter is used in conjunction with a null modem cable. Without a null modem cable, you will not be able to flash the satellite receiver, since the connectors will not match. See the diagram of the null modem cable above.

A null modem cable is a very necessary thing in the satellite industry. Primarily for flashing satellite receivers. But you can’t always buy it, so you have to make it yourself.

As I already said 0-modem cable It will be useful to us primarily for flashing the firmware of satellite receivers. And if for this you can use a short one, which is easier to buy, then for cardsharing through a computer you almost always need a long or very long one (I’ve done it up to 15 m). And it’s better to solder this one yourself. And it is done quite easily.

How to do it yourself null modem cable (RS232) cord for do-it-yourself tuner firmware?

We will need two DB-9F connectors, a soldering iron, solder, a twisted-pair cable, which for me is just right (you can also use another telephone you have on hand), circuits and skillful hands.

There are several connection options, but most often you need a three-pin cable. Well, if this doesn’t work, then we make a complete one for all contacts in accordance with the pictures below.

A non-zero modem cable is almost always suitable. But he also has variations when his contacts go

Contacts 2 – 2 and 3 – 3, 5 -5 direct

Contacts 2 – 3 and 3 – 2, 5 – 5 not direct

It is the latter, indirect, that is most often suitable.

The wiring of the rs-232 com port in satellite receivers can look like both “father” and “mother”.

“Mothers” are much more common, so I advise you to do it with two “mothers” at the ends.

Precisely indirect null modem cable with two mothers, and with a right-to-left calculation, suitable for flashing the firmware of most satellite receivers, or for sharing.