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Low-speed CAN uses resistors at each node. The Morse system uses a single wire between offices. In 1851, a conference in Vienna of countries in the German-Austrian Telegraph Union (which included many central European countries) adopted the Morse telegraph as the system for international communications. The US, however, continued to use American Morse code internally for some time, hence international messages required retransmission in both directions. In 1865, a conference in Paris adopted Gerke's code as the International Morse code and was henceforth the international standard. Early teletypewriters used the ITA-1 Baudot code, a five-bit code. Large telegraphy providers began to develop systems that used telephone-like rotary dialling to connect teletypewriters. At the rate of 45.45 (±0.5%) baud - considered speedy at the time - up to 25 telex channels could share a single long-distance telephone channel by using voice frequency telegraphy multiplexing, making telex the least expensive method of reliable long-distance communication. Interframe space consists of at least three consecutive recessive (1) bits. A 0 data bit encodes a dominant state, while a 1 data bit encodes a recessive state, supporting a wired-AND convention, which gives nodes with lower ID numbers priority on the bus.

Sending: the host processor sends the transmit message(s) to a CAN controller, which transmits the bits serially onto the bus when the bus is free. With different codes, additional operators were required to translate and retransmit the message. The cost of installing wires was ultimately more economically significant than the cost of training operators. There was no need for the wires to be connected back together into a loop, nor the need for hubs or other devices. With both high-speed and low-speed CAN, the speed of the transition is faster when a recessive-to-dominant transition occurs since the CAN wires are being actively driven. The transmitter automatically ran the tape through and transmitted the message at the then exceptionally high speed of 70 words per minute. The signal current moved an iron pen across a moving paper tape soaked in a mixture of ammonium nitrate and potassium ferrocyanide, decomposing the chemical and producing readable blue marks in Morse code.

It embossed dots and dashes on a moving paper tape by a stylus which was operated by an electromagnet. Originally, the armature was intended to make marks on paper tape, but operators learned to interpret the clicks and it was more efficient to write down the message directly. The communicator consisted of a circular dial with a pointer and the 26 letters of the alphabet (and four punctuation marks) around its circumference. Morse and Vail developed the Morse code signalling alphabet. The first system that did not require skilled technicians to operate was Charles Wheatstone's ABC system in 1840 in which the letters of the alphabet were arranged around a clock-face, and the signal caused a needle to indicate the letter. The most expensive aspect of a telegraph system was the installation - the laying of the wire, which was often very long. To prevent a permanent set in the core wire, bend radii should be wide and routing should be straightforward. A transmission would begin with the pointers on the dials at both ends set to the start position. An explicit, unshared shift code prefaced each set of letters and figures. At the sending station, an operator taps on a switch called a telegraph key, spelling out text messages in Morse code.

These resulting systems were called "Telex" (TELegraph EXchange). Wheatstone developed a practical alphabetical system in 1840 called the A.B.C. The optical system was decommissioned starting in 1846, but not completely until 1855. In that year the Foy-Breguet system was replaced with the Morse system. For a brief period, starting with the New York-Boston line in 1848, some telegraph networks began to employ sound operators, who were trained to understand Morse code aurally. Thus the alternating line voltage moved the indicator's pointer on to the position of the depressed key on the communicator. They convert the low voltage direct current (DC) power produced by solar panels into high voltage alternate (AC) power for use by main appliances and rely on the power grid during the night and in bad weather. However, it will not keep the lights working in the evenings if the weather during the day is working against you.

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