Serial cable wire gauge

One byte of async data. Cabling considerations - you should use cabling made for RS data but I have seen low speed data go over ' on 2 pair phone cable. Level 5 cable can also be used but for best distance use a low capacitance data grade cable. The standard maxim length is 50' but if data is async you can increase that distance to as much as ' with a good grade of cable. The RS signal on a single cable is impossible to screen effectively for noise.

By screening the entire cable we can reduce the influence of outside noise, but internally generated noise remains a problem. As the baud rate and line length increase, the effect of capacitance between the different lines introduces serious crosstalk this especially true on synchronous data - because of the clock lines until a point is reached where the data itself is unreadable.

Signal Crosstalk can be reduced by using low capacitance cable and shielding each pair. Using a high grade cable individually shield low capacitance pairs the distance can be extended to '.

At higher frequencies a new problem comes to light. The high frequency component of the data signal is lost as the cable gets longer resulting in a rounded, rather than square wave signal. The maxim distance will depend on the speed and noise level around the cable run.

On longer runs a line driver is needed. This is a simple modem used to increase the maxim distance you can run RS data. Making sense of the specifications Selecting data cable isn't difficult, but often gets lost in the shuffle of larger system issues. Care should be taken. Beyond the obvious traits such as number of conductors and wire gauge, cable specifications include a handful of less intuitive terms. Characteristic Impedance Ohms : A value based on the inherent conductance, resistance, capacitance and inductance of a cable that represents the impedance of an infinitely long cable.

When the cable is out to any length and terminated with this Characteristic Impedance, measurements of the cable will be identical to values obtained from the infinite length cable. That is to say that the termination of the cable with this impedance gives the cable the appearance of being infinite length, allowing no reflections of the transmitted signal. If termination is required in a system, the termination impedance value should match the Characteristic Impedance of the cable.

Systems with long lengths benefits from using low capacitance cable. The value given typically must be multiplied by the speed of light c to obtain units of meters per second.

Plenum cable Plenum rated cable is fire resistant and less toxic when burning than non-plenum rated cable. Check building and fire codes for requirements. Plenum cable is generally more expensive due to the sheathing material used.

The specification recommends 24AWG twisted pair cable with a shunt capacitance of 16 pF per foot and ohm characteristic impedance. It can be difficult to qualify whether shielding is required in a particular system or not, until problems arise. We recommend erring on the safe side and using shielded cable. Shielded cable is only slightly more expensive than unshielded.

There are many cables available meeting the recommendations of RS and RS, made specifically for that application. Another choice is the same cable commonly used in the Twisted pair Ethernet cabling.

Category 5 cable is available as shielded twisted pair STP as well as unshielded twisted pair UTP and generally exceeds the recommendations making it an excellent choice for RS systems. In this document the term RS will be used when refered to this serial interface. As said before RS is a serial interface. It can be found in many different applications where the most common ones are modems and Personal Computers.

All pinning specifications are writen for the DTE side. To make a destiction between all different types of cables we have to use a naming convention. RS can be found on different connectors. There are special specifications for this. All signals are measured in reference to a common ground, which is called the signal ground AB.

A positive voltage between 3 and 15 Vdc represents a logical 0 and a negative voltage between 3 and 15 Vdc represents a logical 1. This switching between positive and negative is called bipolar. The zero state is not defined in RS and is considered a fault condition this happens when a device is turned off.

According to the above a maximum distance of 50 ft or 15 m. This is according to the official specifications, the distance can be exceeded with the use of Line Drivers.

The secondary signals are used on some DCE's. Those secondary channels are mostly of a lower speed than the normal ones and are mainly used for administrative functions.

However, the extra shielding adds diameter and reduces flexibility. Cords with reversible mounting hardware have removable thumb screws to enable a wider range of mounting options than other cords. Mount them to ports and adapters, as well as directly into panels. Transmit data between computers and other devices that have different USB sizes or styles. All USB adapters are backward compatible, so they work with cords and connectors that meet the same or a lower USB standard.

Clear All. Computer Connection Type. Industry Designation. System of Measurement. End Type. Connection Type. End Shape. Shield Type. Cord OD. Cord Length. These would be correct if you were trying to connect the serial port in the back to the "standard" serial port from the CP, but that isn't what you're trying to do. The second is that the Tx pin from the ADM pin 12 and the Tx pin from the CP pin 21 and the ohm resistor will be in contention with each other, I think.

You normally wouldn't be able to connect both together without one loading down the other, making the serial data from your computer to the CAT interface unreliable. One solution to this problem, if you are absolutely not going to use the CAT interface on the rear of the radio, would be to lift pin 12 of Q ADM and connect your jumper wire to the PC board not the pin of the ADM, it would just be left floating.

Another solution would be to create a "diode-OR" type configuration, since I believe that the data pins are "active low" confirm this before going forward with this suggestion. You'd first lift pin 12 of Q like above. Then install one signal-type diode think 1N with the cathode on pin 12 of Q and the anode on the PC board pad under pin Again, this will only work if the data is active low inverted because the diode configuration I've described assumes that the outputs of the CP and the ADM are at 3.

Once more, please confirm my belief here before you take this approach. This is definitely an interesting idea, and I'm definitely interested in looking into your original discovery as well using a separate USB-to-serial adapter to see how that works.

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