Guide d’Installation sonde E4000
E4000 probe Installation Guide
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ANNEXES
1. Installation of BUS connections
1.1
RS485
RS485 Modbus connection is not optically isolated. Therefore, you must pay special attention during
the installation procedures that they do not cause communication failures or does not damage the RS485
coupler. Follow the points in the table below to ensure proper operation of your communication.
1
Use a shielded bus cable and connect one end of the shield to ground. Make sure, wherever
possible, that there is no break in the cables. If this is not possible, you must have shield continuity
consistent with the EMC at the connection points.
2
Keep RS485 cables away from other cables like power cables for example.
3
Connect the shielding to one end grounded to ensure equipotentiality of the shield.
No other grounding is required.
The "Shield" terminal of the power supply terminal block is isolated and is intended to facilitate the
continuity of shielding.
THE SHIELD BUS MUST NOT BE CONNECTED TO THE “-“ OF THE BUS.
Warning: If you do not comply with above, the interface may be destroyed.
4
Make sure electrical signals are correct for the bus cable. This sets the resting level of the signal
between two posts and is important for identifying the beginning of a message. The E4000 probe
produces a 5V electrical signal. The voltage between the data lines + (B) and - (A) should be
between 0.5 and 1V.
5
For bus cable lengths over 100m, make sure to activate the bus termination at both ends. A bus
termination on one side only is sufficient for shorter distances. Bus termination, on E4000 probe
side, is provided by a jumper (see picture below).
6
The polarization of the bus is also highly recommended using the two other jumpers.
RS485 standard requires a differential level of 200 mV for the signal detection. If the RS485 is not
polarized, this level will not be reached at rest (without communication on the line) and then the
operation will not be guaranteed. For this, a bias is applied to only one point of the bus. It is
preferably applied to the master side.
RS485 Modbus Connection
Activation of the RS485 bus termination
and polarization by placing three
jumpers.
-
(A)
+ (B)
Shielding of the cable
*
cable
* : Never connect to the – of the power supply.
