Gaussmeter IGM11 Operating Instructions
Chapter 9 Serial Interfaces
Page 50 / 106
MAGSYS
magne t
systeme
Version 01/2013
© 2013 MAGSYS magnet syste
me GmbH - All Rights Reserved.
If the power supply of the interface is 5 V, we recommend 390
Ω
resistors (with 15 V
approx. 1 k
Ω
to power supply and 390
Ω
to common ground).
Figure 25 EIA-485 Shielding and Potential Equalization
9.3.3
EIA-485 Cable Details
A shielded, twisted two-wire line is used for the bus wiring.
The following parameters are recommended for the cable:
Conductor cross section
2 × 0.5 mm²
Stranded wire
≥ 16× ≤ 0.2 mm
Stranding
≥ 20 twisting rotations/m
Total shielding
Mesh wire, tinned copper wire
⌀
≥ 1.1 mm²,
≥ 85 % optical cover
Conductor resistance
≤ 40 Ω/km
Insulation resistance
≥ 200 MΩ/km
Operating voltage
≥ 300 V
Test voltage
≥ 1500 V
Load capacity
≥ 5 A
Capacity
≤ 120 pF/m
Line length
≤ 1200 m
9.3.4
EIA-485 Wiring Details
When wiring the bus cable pay attention to an EMC-compatible assembly.
•
The bus line can be layed in one cable channel together with other data lines
and unshielded lines for DC less than 60 V and unshielded lines for AC less
than 25 V.
•
The bus line must not be layed together with unshielded lines for DC
between 60 V and 400 V. In this case, a minimum distance of 10 cm should
be maintained.
•
Keep a minimum distance of 1 m from electric sources of interference.
•
The cables should be layed as short as possible between two devices.
Data line
Ground
Shielding
Potential equalization
Bus terminal
Trial Version
Subje
ct to chan
ge
