Chapter H: H: H1 Hysteresis Plus Dead Band

H1: A fieldbus network that operates at 31.25 kbit/ second. Generally, it is a lower-speed and lower-cost network than H2.
H1 field device: A fieldbus device that is connected directly to an H1 fieldbus. Typical H1 field devices are valves and transmitters.
H1 repeater: An H1 repeater is an active, buspowered, or non-bus-powered device that is used to extend the range over which signals can be correctly transmitted and received for a given medium. A maximum of four repeaters and/or active couplers can be used between any two devices on an H1 fieldbus network.
H2: A proposed ISA SP50 (fieldbus) standard for communications at the controller level of hosts. It has been superseded by the HSE (High Speed Ethernet) protocol.
hacking: In computers, writing programs or using computer communicating for fun. Through misuse in the news media it has come to mean only the indiscriminate and unauthorized accessing of other computers over public networks.

See also cracking.
hair-line cracks: Fine, random cracks in a coating such as paint or in any rigid surface.
hairline register: In the composition of screen displays and printing, alignment within 1/ 2 row of dots.
half-adder: A logic circuit that accepts two binary input signals and produces corresponding sum and carry outputs. Two half-adders and an OR gate can be combined to realize a full-adder.

See also full adder.
half-adjust: To round a number so that the least significant digit or digits determine whether or not a one (1) is to be added to the...

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The Automation, Systems, and Instrumentation Dictionary, Fourth Edition

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Chapter H: H: H1 Hysteresis Plus Dead Band

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