PROFIBUS问题解答22例-专业自动化论坛-中国工控网论坛

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发表于：2006-05-19 11:52:00

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先给大家提供英文的，以后给大家提供中文的。 1. What Bus type does your system implement. Examples CMSA/BA, CMSA/CD, master/slave, multiple masters etc. PROFIBUS is based on a Token principle with underlying Master/ Slave communication (hybrid media access). Services: SDN-Send Data with no acknowledge (can be used for multicast/broadcast) SDA- Send Data with acknowledge SRD- Send and Reply with Data (for efficient bi-directional data transfer)

2. What is the maximum number of nodes that the network can support. PROFIBUS allows up to 32 nodes per segment and up to 126 nodes for one network.

3. What is the Bus topology. The base technology is a line which allows connection and removal of nodes at any time without breakdown. PROFBUS allows ring and star topology as well with fiber optics. 4. What is the maximum transmission distance without repeaters. What baud rate is supported at this maximum distance. The maximum distance would be 1000m by using copper with baudrates between

The maximum length may be extended with fiber optic links (up to 2300/15000 m per link) 5. What types of transmission media are used and supported. · Copper cable (shielded twisted pair- known as IBM type 1 cable) · solid and stranded cable · specialized materials for plastic surrounding · fiber optic · in glass · in plastic · Infrared 6. How many bits are allocated at a node for input and output data. PROFIBUS allows between 0 and 244 byte, determined by the device requirements for input and output each. 7. How is the bus powered. There is no specialized bus power supply. The terminal resistors with pullup and pulldown are located at the end of the line and powered be the devices on that place. One combination is enough to run the system. 8. If the bus provides power to field devices what current level is available. PROFIBUS PA does supply power for intrinsic safe devices connected with twisted pair. This is done according to IEC 1158-2 specification (maximum current is 120 mA per coupler for intrinsic safe operation and >300mA for non intrinsic safe operation). 9. How are node addresses set. Two methods are supported: · DIP switches or similar techniques · setting of the node address via the bus connection Any choice is possible 10. Does the bus provide duplicate address detection. Configuration checks for duplicate addresses. Masters will look for duplicate addresses before entering the token ring and when unexpected frames are received. Slave must be set up with their ident-number and with their configuration. In case of a mismatch, this will be reported to the masters application. 11. Does the bus provide an address attendance check after the first scan. · through a so called live list · scanning of configured slaves is done cyclic · scanning for new masters is executed all time 12. Does the bus provide a node configuration check after the first scan. Yes, with the function config_check after power up. In addition, the ident number is also checked. 13. Does the bus provide error detection and correction algorithms. PROFIBUS has a variety of error detection capabilities · Checkbits in every byte · Checksum for every message · Startdelimiters for efficient frame detection · Addressing information (source and destination) · Inactivity detection to find out the beginning · Transmitter check at the master devices · Monitoring the token passing procedures · The error correction is done by retries. · PROFIBUS includes message duplication capabilities 14. Can a node provide parameter programming. Examples logic inversion and similar Boolean operations. Explain any extended detection. There are several ways for parameter setup: · PROFIBUS allows the individual set of par