Search results
Results From The WOW.Com Content Network
A major application of current loops is the industry de facto standard 4–20 mA current loop for process control applications, where they are extensively used to carry signals from process instrumentation to proportional–integral–derivative (PID) controllers, supervisory control and data acquisition (SCADA) systems, and programmable logic ...
A digital current loop uses the absence of current for high (space or break), and the presence of current in the loop for low (mark). [1] This is done to ensure that on normal conditions there is always current flowing and in the event of a line being cut the flow stops indefinitely, immediately raising the alarm of the event usually as the heavy noise of the teleprinter not being synchronized ...
In multi-drop mode the analog loop current is fixed at 4 mA and it is possible to have more than one instrument on a signal loop. HART revisions 3 through 5 allowed polling addresses of the instruments to be in the range 1–15. HART revision 6 allowed addresses 1 to 63; HART revision 7 allows addresses 0 to 63.
In process automation traditionally most of the field transmitters are connected over a current loop with 4-20 mA to the controlling device. This allows not only to transmit the measured value with the level of the current, but also provide the required electrical power to the field device with just one two-wire cable of a length of more than a ...
For example, on the original IBM PC, a male D-sub was an RS-232-C DTE port (with a non-standard current loop interface on reserved pins), but the female D-sub connector on the same PC model was used for the parallel "Centronics" printer port. Some personal computers put non-standard voltages or signals on some pins of their serial ports.
4-20mA current loop, used in industrial control and automation. 3.5 inch and 2.5 inch hard drives. 19-inch rack standards for telecommunication, server, storage, audio, music, video, and power equipment. ATX motherboard, back plane, and power standards.
IEC 62056-4-7:2014 DLMS/COSEM transport layer for IP networks; IEC 62056-5-3:2017 DLMS/COSEM application layer; ... usually modulated by a 20mA current loop.
The VT200s were the last DEC terminals to provide a 20mA current loop serial interface (using a 8-pin Molex-style connector), an older standard originally developed for the telegraph system but became popular on computers due to the early use of Teletype Model 33's as ad hoc terminals. A standard 25-pin D-connector was also provided for RS-232.