VEGA WEIGHTRAC 31 Profibus PA - Manual (Page 28)

28
5 Connecting to power supply
WEIGHTRAC 31 • Profibus PA
43837-EN-131119
5 6 7 8
2
3
4
1 2 +
( ) (-)
1
Fig. 15: Adjustment and connection compartment (Ex-ia) with instruments with
intrinsically safe current output
1 Terminals for Profibus PA
2 Contact pins for the display and adjustment module or interface adapter
3 Terminals for the external display and adjustment unit
4 Ground terminal
5.3 Connection - Summation
Several instruments can be cascaded to measure also broad con-
veyor belts. The measuring ranges of the instruments must overlap.
Cascading means that two or several instruments are connected
which can together cover a longer measuring range.
The instrument acts as Master and all other instruments operate as
Slaves.
The pulse rates of all instruments are summed in the Master instru-
ment and converted into a common signal.
The Master instrument must have the function "Mass flow detection".
For this purpose, select under the menu item "Setup/Application" the
function "Mass flow detection".
Set the address setting (MGC) on the Master instrument to "0 - 0".
For this purpose, the Slave instruments must be defined as "Slave".
Select under the menu item "Setup/Application" the function "Sum-
mation Slave".
The address setting (MGC) on the Slave instruments can be freely
selected. Only the address "0 - 0" is reserved for the Master instru-
ment.
Connect the instruments according to the following wiring plan:
Adjustment and connec-
tion compartment - In-
struments with intrinsi-
cally safe current output
Electronics and terminal
compartment - summa-
tion