Wiring
17
V1 Definition
V1 fieldbus is a voltage mode digital communication using up to ±30 V
DC
, and requires the
following three electrical connections between each of the devices on the bus:
V1 Cable specification
4.3.4 Additional information on Whessoe WM550
The WM550 communication protocol works using a current loop principle.
"
Caution!
Please take care that the signal and power cables always are separated to prevent noise and electrical
interference between them.
Connection
Please take into consideration that the principle of current loop connection works as follows:
The Tankvision (master) (-) signal point connects to slave 1 (+) signal point. Slave 1 (-) signal point
connects to slave 2 (+) signal point until (the last) slave N (-) signal point connects back to the
Tankvision (master) (+) signal point closing the current loop.
Cable specification
Please ensure to follow the following recommendations for field installation of the Tankvision with
the WM550 protocol variant
• Cable with twisted and non-shielded pairs
• Cable with at least 0,5 mm² (20 AWG) section
• Maximum total cable resistance: 250 Ω
• Cable with low capacitance
Signal Purpose Remarks
A Data signal (-)
These signals must be connected using a balanced twisted pair cable.
B Data signal (+)
Shield EMC protection Copper braided or combined foil and braided shielding
Cable capacitance ≤ 50 nF/m
Core cross-section ≥ 0.9 mm
2
(AWG 17) multi-strand cable is preferred
Cable type twisted pair
Cable resistance ≤ 30 Ω/km
Shielding Copper braided shielding or combined foil and braided shielding
Insulation ≥ 60 V
DC
Terminal Signal Purpose Remarks
10 - Data Signal Current Loop (-)
11 + Data Signal Current Loop (+)
Cross section (mm² (AWG)) Resistance (Ω/km) Capacitance (nF/km)
Cable 1 0,5 (20) 39.2 60
Cable 2 0,75 (18) 24.6 65
Cable 3 1,3 (16) 14.2 75
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