Com null modem cable. Null modem cable for satellite receiver

GREENCONNECT Russia – manufacturer of link, modem and NULL modem cables 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 model range manufactured products.

Usage modem or null modem cables for device control Cisco or game consoles, terminals, cash terminals, various devices control 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, just like 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.

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). Modern Monitor The serial port can feature both sides of full 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.

Installing a 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. operating system To match the computer to the receiver, you can use 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 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 driver software disc. 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.

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 on 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 RS-422 interface, and then back to RS-232, which allows it to be used as physical media two pairs of wires.
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 serial port PC, then use a straight cable - that is, with a 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 disabled; Likewise, if a DIP switch is used to "disable reply", make sure 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 sending/receiving data to the specified contacts.
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 to the computer hexadecimal code 7B; 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 completed 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 an operating room Windows system NT4.0 (and below) additional measures must be taken. This system does not have plug-in functionality and play"and therefore setting up computer ports in 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 working 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 products in our range allow you to control multiple devices when they are serial connection straight cables - which seems wrong in light of the above! In fact, we configure the devices in master/slave modes, with only one, the master device, 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 using the RS-232 interface.)

Manufacturers of satellite tuners (receivers) are constantly improving their software. At the same time, they correct errors, improve image and sound quality, and add new functions to the menu. And to update the firmware in the tuner (receiver), you need to use a computer and a zero modem to replace the old software in the tuner’s flash memory with new one.

Updating your receiver with new software is possible via a zero modem cable, which is not difficult to make yourself at home. In popular parlance, this is called firmware satellite tuner. For tuners equipped with an rs-232 connector, updating software, keys, removing a full dump, restoring the tuner's functionality. In most cases it is used only with a null modem cable. To connect the receiver, you will need a computer with a com port, or a laptop with a usb-com adapter. The operating system used to match the computer and the satellite tuner is windows 98, windows xp, windows 7 x32/x64 bit or higher.

Be careful! Connect and disconnect the rs-232 cable from the receiver only when it is disconnected from the network AC voltage 220 volts. During a firmware update, never interrupt the software update process. All this can lead to failure of the flash memory of the satellite receiver.

Let's return to the null modem cable. The scheme is very simple. Everything is shown in great detail in the photographs. When making a null modem cable, you will need 2 rs-232 connectors (female connector type) - the cost is low. Sold at any computer store. A cable with three cores and preferably with a screen. Can be used twisted pair UTP type category 5e. It is very important that the cable is shielded, this will provide stability when working with it. All this can be assembled and soldered using the photographs on our website.

Below in the photo is a null modem cable for a satellite receiver with soldered connectors. 3 wires and a screen are involved.