19
4 Connecting to power supply
FIBERTRAC 31 • Four-wire 4 … 20 mA/HART
62067-EN-211203
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 intrinsically safe signal output 8/16 mA/HART (Multidrop) ac-
tive
2 Contact pins for the display and adjustment module or interface adapter
3 Terminals for the external display and adjustment unit
4 Ground terminal
If inductive loads or stronger currents are switched through, the gold
plating on the relay contact surface will be permanently damaged.
The contact is then no longer suitable for switching low-voltage
circuits.
Inductive loads also result from the connection to a PLC input or
output and/or in combination with long cables. It is imperative that you
take measures to extinguish sparks to protect the relay contact (e.g. Z
diode) or the transistor or 8/16 mA output.
4.4 Connection - Summation
To measure the level in very high vessels, multiple instruments can be
cascaded.
Cascading means that two or several instruments are connected
which can together cover a longer measuring range.
The instrument acts as Primary and all other instruments operate as
Secondaries.
The pulse rates of all instruments are summed in the Primary instru-
ment and converted into a common signal.
The Primary instrument must have the function "Level". For this pur-
pose, select under the menu item "
Setup - Application
" the function
"Level".
Set the address setting (MGC) on the Primary instrument to "99".
For this, the Secondary instruments must be defined as "Summation
Secondary". Select under the menu item "
Setup - Application
" the
function "Summation Secondary".
The address setting (MGC) on the Secondary instruments can be
freely selected. Only the address "99" is reserved for the Primary
instrument.
Adjustment and connec-
tion compartment - In-
struments with intrinsi-
cally safe current output
Connection to a PLC
Electronics and connec-
tion compartment - sum-
mation
