Serial modem cable

This cable could be used with more software but it had no actual enhancements over its predecessor. The software would work thinking it had hardware flow control but could suddenly stop when higher speeds were reached and with no identifiable reason.

In this cable the flow control lines are still looped back to the device. The only way the flow control signal would reach the other device is if the opposite device checked for a Carrier Detect CD signal at pin 1 on a DE-9 cable and pin 8 on a DB cable.

As a result, only specially designed software could make use of this partial handshaking. Software flow control still worked with this cable. With suitable software, the cable is capable of much higher speeds than its predecessors. It also supports software flow control. A virtual null modem is a communication method to connect two computer applications directly using a virtual serial port. Unlike a null modem cable, a virtual null modem is a software solution which emulates a hardware null modem within the computer.

There are some advantages to this:. Another common example consists of Unix pseudoterminals pty which present a standard tty interface to user applications, including virtual serial controls. Two such ptys may easily be linked together by an application to form a virtual null modem communication path. Search for:. A null modem adapter. This is usually a serial and null modem cable problem.

Null Modem cables look like straight serial cables and the only way you can tell the difference by looking is most Null Modem cables are marked with 'NM' or 'Null Modem'. Be sure you are plugging into the telephone modem one. For the IIgs, you will also need to verify a couple of things in the control panel. If you are building your own cable, this is the pinout to use. It describes the round "MiniDIN8" male connector looking into the cable at the pins:.

A single-cable null-modem is wired like this Apple would call this a "Printer" cable :. You will need a serial cable setup that ultimately connects the round, 5-pin DIN modem connector of your IIc, Laser , or Franklin Ace to the serial or USB port of your host computer - and also performs a null-modem function in between. If you would like to purchase a null modem that is ready to use, click here. Be sure you are plugging into the telephone modem one, on the far left as you look at the back of the IIc:.

If you are wiring a null-modem yourself, the following is the pinout to use. This pinout describes the round male connector looking into the cable at the pins. Note that this is numbered using Apple's not DIN's! This null modem cable ties all the handshaking lines together at the host end and at the Apple end. This effectively disables hardware handshaking. There are two pinouts for a single-cable null-modem that will work with ADTPro: an "Imagewriter I" cable one that does some amount of "hardware handshaking" and one without.

The Apple IIc's hardware handshaking tends to be problematic and non-standard, so we're only discussing the non-hardware handshaking cable here. Price: 3. Quantity: Qty:. Price: 4. Price: 5. With a null modem connection the transmit and receive lines are crosslinked. Depending on the purpose, sometimes also one or more handshake lines are crosslinked. To tell if your cable is null modem or straight though, you can search the part number at ni.

Alternatively you can use a hand held DMM to test continuity on the individual pins of your serial cable. Rollover cable also known as a Yost cable , Cisco cable , or a Console cable is a type of null - modem cable that is often used to connect a computer terminal to a router's console port. This cable is typically flat and has a light blue color to help distinguish it from other types of network cabling.

Asked by: Kristi Falten asked in category: General Last Updated: 18th April, What is the difference between null modem and rs cables? Null modem , also called crossover, is a term associated with serial RS cables. A standard serial cable , also called an AT cable , has the wires inside the cable running straight through.

Take a DB9 cable as an example. Pin 1 on one end of the cable would be connected to Pin 1 on the other end. Is null modem cable straight through? Null modem, also called crossover, is a term associated with serial RS cables.

A standard serial cable, also called an AT cable, has the wires inside the cable running straight through. What is Modem explain?