There is no fixed answer. Many factors play a role, the maximum cable length connecting devices together. The biggest problem with using long cables is that the cables become more vulnerable to noise interference. This is due to the capacitance of the cable. The cable works like an antenna, and there will be loss of power through the cable. The maximum distance of the cable can be obtained, and the following basic wiring principles must be followed. Keep the cable away from objects that produce a large amount of electrical noise. This includes AC motors, arc welding machines, AC power lines and transformers. Twisted pair cable shall be used when using complementary signals, and shielded cable shall be used when using any type of signal. The output voltage uses the maximum allowable voltage.

For example, if the encoder can output 5 to 24 volts, use 24 volts. Open or differential receiver using collector (pm28s00) is used together with the differential line driver output to obtain the maximum drain / source current source. If you are using an encoder as an input to more than one controller, use a signal amplifier. This is also a good way to improve the distance of signal transmission. When using differential input, the maximum distance of a typical differential line driver is about 100 inches The distance of open collector is about 35 feet.

As the name suggests, this output chip comes from "driving" current to the line. Unlike the open collector output, the line driver chip actively drives the output high or low. Therefore, the load can generate leakage and source current. The main advantage is its line driving ability, which pushes higher current through the cable and makes the cable run longer. Although line drivers can be used in single ended formats (i.e. push-pull output), they are the most commonly used complementary or differential signals. When using differential signals, line drivers are preferred when using shielded twisted pair cables, using longer cables or in high noise environments. 7272 7 272 is perhaps one of the most widely recognized line drivers. The chip is used in many competitive encoders and good reasons; 7272 achieves good performance The tradeoff between current capability, available voltage range, and chip cost. The typical current output capability of the 7272 chip is in the range of 40-50ma, which is suitable for cable operation in the vicinity of 50-75 feet.

In addition, the general supply of the 7272 chip provides a "mirror voltage" output, in other words, regardless of the voltage input to the encoder, Similarly, the output voltage (minus a small amount, taking into account the power requirements of the encoder). Another notable feature is its 7272 temperature protection function. If the 7272 is driven to the limit (high load, high voltage limit, high frequency) to increase the temperature, it will enter the protection mode and start "exit" Or stop the output. If it is allowed to cool, the chip will restart, much like a thermal switch, and begin to operate.

However, too much will cause the reset threshold or start point to decrease over time, eventually leading to the unreliability of the encoder. In short, if the application continues to cause such downtime, other different line drivers should be selected. 4469 4469 is another very prominent line driver option. Unlike the 72724469, it has much higher current driving capacity, depending on different manufacturers, usually in the range of 100mA. This is a clear advantage and can be applied to longer cable runs, usually at 100-300 feet. However, this higher current capability is accompanied by a disadvantage. 4469 wastes so much energy that the voltage range is affected with high current. A typical mirror voltage output is limited to 15Vdc. If an adjustable 5V output is selected, the input voltage can be increased to 24V. As for costs, 4469 and 7272 are comparable. In addition, the 4469 has no automatic protection function. It can drive with all its strength without worrying about shutdown, but it will have a significant adverse impact on its service life.