Device description
20
MA 255
i
Le
u
ze electronic
DeviceNet installation
Up to 64 network devices can communicate with one another in a DeviceNet network with
baud rates of 125, 250 or 500 kBaud. In addition to the two signals for data transmission—
CAN-L and CAN-H—the DeviceNet cable also includes two cables for supplying the
DeviceNet network device with 11 … 25 V DC-volt. The connection of the MA separates the
operating voltage and the field bus voltage, the transmission electronics, however, require
V+ and V- via the CAN cable.
The maximum length of the DeviceNet cable is dependent on the selected cable type and
baud rate.
Listed in the table are the max. network expansions as a function of the used data line
without repeater.
The ready-made data lines from Leuze electronic correspond to the thin cable.
Communication
The gateway MA 255
i
supports the CIP-based DeviceNet protocol and requires the EDS
file (
E
lectronic
D
ata
S
heet) for communication; it is provided in the Download area of the
Leuze home page.
You can find the EDS file at:
www.leuze.com -> Download -> identify -> Modular interfacing units.
The EDS file is named "MA255i.eds"; the corresponding icon is named "MA255i.ico".
The EDS file includes all communication parameters of the participants as well as the avail-
able objects. The DeviceNet communication tool reads the EDS files of the participants
present in the network and uses this information to calculate the configuration data that is
subsequently loaded onto the participants.
The input/output data is addressed according to the following fundamental scheme:
1.
Device address (MAC ID)
The participant is addressed with its MAC ID, which is unique in the network.
2.
Object class identifier (class)
Used as the basis for addressing the desired object class.
3.
Object instance identifier (instance)
Addressing of the object instance within the object class.
4.
Attribute identifier (attribute)
Addressing of the attribute within the object instance.
5.
Service code (get, set, reset, start, stop and others...)
The maintenance code ultimately describes the type of access to the data, e.g.,
reading or writing.
Transmission rate
125 kbit/s
250 kbit/s
500 kbit/s
1
1)
1)
Thick cable =1
2
2)
2)
Mid cable = 2
3
3)
3)
Thin cable = 3
1
2
3
1
2
3
Max. length of master line (trunk line) in m
500
300
100
250
100
100
Max. length of stub cable (drop line) in m
6
6
6
Max. length of all sub cables per network in m
156
78
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