Bray 70 Series SERVO PRO DeviceNET - Manual (Page 13)

S70 DeviceNet Servo Installation & Maintenance Manual
2000 BRAY CONTROLS Page 12 of 24
as a Class 2 circuit. This requires limiting the current in any section to 4 amps. The rating of
the system components themselves, however, is 8 amps.
The trunk-line can be constructed of either thick cable or thin cable. A combination of both thick
and thin cable can be used provided that only one type of cable is used for any section of cable
(length between two power taps or between a power tap and the end of the trunk line).
There are several items that can limit the current available on the network. More than one of
these limits can independently exist at the same time:
The 8 amp current limit of thick cable
The 8 amp current limit of mini-style connectors
The 3 amp current limit of thin cable
The 3 amp current limit of micro-style connectors
The maximum common mode limit of the transceiver*
*simply put, this parameter limits the voltage drop that can be tolerated on the power cable. The
current that corresponds to the maximum common mode voltage drop is indicated in Table 4
and Table 5.
Network
Length m
(ft)
0
25
(82)
50
(164)
100
(328)
150
(492)
200
(656)
250
(820)
300
(984)
350
(1148)
400
(1312)
450
(1476)
500
(1640)
Maximum
Current in
Amps
8.00 8.00 5.42 2.93 2.01 1.53 1.23 1.03 0.89 0.78 0.69 0.63
Table 4: Maximum current based upon thick cable network length
Network
Length m
(ft)
0
10
(33)
20
(66)
30
(98)
40
(131)
50
(164)
60
(197)
70
(230)
80
(262)
90
(295)
100
(328)
Maximum
Current in
Amps
3.00 3.00 3.00 2.06 1.57 1.26 1.06 .91 0.80 0.71 0.64
Table 5: Maximum Current Available based upon Thin Cable Network Length
The network power supply can be placed at the end or at the center of the network. By
examining the current requirements of the network, the power supply should be placed such
that the maximum current specification is not exceeded.