This online course covers mechanical, hydraulic, pneumatic, and telemetric data transmission methods. Discusses indicators, other devices, and methods used for electrical/electronic data transmission in detail.
– List the advantages and disadvantages of mechanical, hydraulic, and pneumatic data transmission. – Compare voltage-loop and current-loop transmission for analog data and explain the importance of resolution for digital data transmission. – List the advantages and disadvantages of optical and telemetric data transmission.
Compares methods and standards for parallel and serial digital data transmission. The course describes optical isolation and the operation of optical data transmission systems in detail. Provides specific methods for preventing common kinds of data transmission interference. Data Transmission is available in and formats.
TPC Training Systems is authorized by IACET to offer 0.5 CEUs for this program. Review a full course list for.
Lesson 1 - Process Data Transmission Methods Topics: Data handling; Local and remote indicators; Mechanical, hydraulic, pneumatic, electronic, optical - and telemetric data transmission Learning Objectives: – Describe the differences between data transmission in open- and closed-loop systems and with local and remote indicators. – Discuss the differences among analog, digital, and discrete control. – Discuss the use of intrinsically safe and explosion-proof equipment.
– List the advantages and disadvantages of mechanical, hydraulic, and pneumatic data transmission. – Compare voltage-loop and current-loop transmission for analog data and explain the importance of resolution for digital data transmission. – List the advantages and disadvantages of optical and telemetric data transmission. Lesson 2 - Electrical Data Transmission Topics: Analog and digital data; Electronic PV indicators; Signal conditioning and conversion; Compensation; Span and zero adjustment; Linearization Learning Objectives: – Compare analog and digital data representation. – Discuss uses for bar graph displays, CRT displays, recorders, and data loggers.
– Describe the characteristics of the electrical output signals from analog sensors and transducers, using a strain gauge as an example. – Discuss the significance of the common-mode rejection ratio in signal conditioning. – Describe the processes of signal conversion, compensation, zero and span adjustment, linearization, and conversion to engineering units. Lesson 3 - Digital Data Transmission Topics: Number systems; Data formats; ASCII; Error correction; Analog-to-digital conversion; Distributed process control; Parallel and serial data transmission Learning Objectives: – Discuss the differences between analog and digital data forms.
– Discuss several reasons for using digital data. – Describe methods used to interface process control data signals to a communications network.
– Explain how analog data are converted to digital form for transmission and display. – Discuss the differences between parallel and serial data transmission systems. Lesson 4 - Optical Data Transmission Topics: Fiber optic cable, connection, and transmission advantages; Optical propagation; Installation of cables; Light sources; Detectors; Standards Learning Objectives: – Name the basic elements in a data transmission system based on light energy. – Explain how optoisolators work and why they are used.
– Describe the advantages and disadvantages of optical data transmission. – Explain how light rays are propagated down glass fibers. – Discuss connection and installation methods for fiber optic cables. – Discuss the selection of light sources and detectors.
Lesson 5 - Data Transmission Interference Topics: Electrical and process noise; Signal-to-noise ratio; Power line noise; Electromagnetic interference; Capacitive coupling; Ground loops; Noise reduction techniques; Electrostatic shielding Learning Objectives: – Define electrical noise, process noise, and the signal-to-noise ratio. – Explain how ac power lines, EMI, capacitive coupling, and ground loops cause electrical noise. – Describe two kinds of noise filters and explain three methods of reducing ac power line noise. – Compare methods for reducing electromagnetic and electrostatic coupling. – Discuss the use of differential measurements and the CMRR.
– Describe ways of reducing ground loop noise and RFI and explain when optical coupling might be used.
Contents. The need for synchronization Whenever an transmits digital (and sometimes analog) data to another, there must be a certain rhythm established between the two devices, i.e., the receiving device must have some way of, within the context of the fluctuating signal that it's receiving, determining where each unit of data begins and where it ends. Methods of synchronization There are two ways to synchronize the two ends of the communication. The synchronous signalling methods use two different signals. A pulse on one signal indicates when another bit of information is ready on the other signal.
The asynchronous signalling methods use only one signal. The receiver uses transitions on that signal to figure out the transmitter bit rate (') and timing, and set a local clock to the proper timing, typically using a (PLL) to synchronize with the transmission rate.
A pulse from the local clock indicates when another bit is ready. Synchronous transmission In synchronous communications, the stream of data to be transferred is encoded as fluctuating voltage levels in one wire (the 'DATA'), and a periodic pulse of voltage on a separate wire (called the 'CLOCK' or 'STROBE') which tells the receiver 'the current DATA bit is 'valid' at this moment in time'. Practically all protocols use synchronous transmission. For example, in a computer, address information is transmitted synchronously—the address bits over the, and the read or write 'strobe's of the. Single-wire synchronous signalling A logical one is indicated when there are two transitions in the same time frame as a zero. In the Manchester coding a transition from low to high indicates a one and a transition from high to low indicates a zero.
When there are successive ones or zeros, an opposite transition is required on the edge of the time frame to prepare for the next transition and signal. Asynchronous transmission The most common asynchronous signalling, signalling, uses a near-constant 'bit' timing (+/- 5% local oscillator required at both end of the connection). Using this method, the receiver detects the 'first' edge transition. (the START BIT), waits 'half a bit duration' and then reads the value of the signal. A further delay of one 'whole bit duration' is executed before the next data bit is 'read' - repeating for length of the whole serial word (typically 7/8-data bits). Finally an optional STOP bit is appended to identify the end of the data word. The word structure used in typical asynchronous serial communications is START-DATA0:7-STOP0:1 (followed by an optional PARITY bit).
These formatting variables are specified when configuring the transmit and receive nodes before communications take place. The bit duration is determined from the nominated 'bit rate' in bps.
300, 1200, 9600, 19200, 115200 etc. The use of the word BAUD is not strictly correct in the modern application of serial channels. Special level & timing conditions are detected to identify an open-circuit condition (BREAK) The sync token might be a single pulse (a 'start bit' as noted above), or it may be a more complicated or such as.
Advantages and disadvantages Advantages Disadvantages Asynchronous transmission. Simple, doesn't require synchronization of both communication sides. Cheap, because asynchronous transmission requires less hardware. Setup is faster than other transmissions, so well suited for applications where messages are generated at irregular intervals, for example data entry from the keyboard, and the speed depends on different applications.
Large relative overhead, a high proportion of the transmitted bits are uniquely for control purposes and thus carry no useful information Synchronous transmission. Lower overhead and thus, greater throughput.
Slightly more complex. Hardware is more expensive References.