Renu Electronics GWY-500, User Manual

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Getting Started
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Doc No: UMAN\GWY-500-B\0106
REVISION 4
Layer 1, 2 and user PROFIBUS-DP uses layers 1 and 2, and the user interface. Layers 3 to 7 are not
interface defined. This streamlined architecture ensures fast and efficient data transmission. The
application functions which are available to the user, as well as the system and device
behaviour of the various PROFIBUS-DP device types, are specified in the user interface.
Transmission medium RS-485 transmission technology or fibre optics are available for transmission. RS-485
transmission is the most frequently used transmission technology. Its application area
includes all areas in which high transmission speed and simple inexpensive installation
High-speed, inexpensive are required. Twisted pair shielded copper cable with one conductor pair is used.
Easy installation The RS-485 transmission technology is very easy to handle. Installation of the twisted
pair cable does not require expert knowledge. The bus structure permits addition and
removal of stations or step-by-step commissioning of the system without influencing the
other stations. Later expansions have no effect on stations which are already in opera
tion. Transmission speeds between 9.6 kbit/s and 12 Mbit/s can be selected. One
unique transmission speed is selected for all devices on the bus when the system is
commissioned.
Cable length The maximum cable length depends on the transmission speed The specified cable
lengths are based on type-A cable. The length can be increased by the use of repeaters.
The use of more than 3 repeaters in series is not recommended.
3.1.2 Device Types
PROFIBUS distinguishes between master devices and slave devices.
Master devices Master devices determine the data communication on the bus. A master can send
messages without an external request, as long as it holds the bus access right (the
token). Masters are also called active stations in the PROFIBUS standard.
DPM1, DPM2 There are two types of master devices: DP master class1 (DPM1) and DP master class2
(DPM2). A DPM1 is a central controller which exchanges information with the
decentralised stations (i.e. DP slaves) within a specified message cycle. DPM2 devices
are programmers, configuration devices or operator panels. They are used during com
missioning, for configuration of the DP system, or for operation and monitoring purposes.
Slave devices Slave devices are peripheral devices. Typical slave devices include input/output devices,
valves, drives, and measuring transmitters. They do not have bus access rights and they
can only acknowledge received messages or send messages to the master when
requested to do so. Slaves are also called passive stations.