Simtronics MultiFlame DF-TV7-T Operating Manual page 24

4.3.6. 4-wires connection (isolated power)
Fire or control system
-
+24VD
+
-
+
A
+24VD
Typ < 450
Ω
When using a 4 wires connection, the current loop is provided by the input module or PLC.
The loop (L + and L-) is optically isolated from the detector. 4-20mA or 0-22mA input module
of the PLC has to power up the current loop with, at least 8V at the terminal level, for 22 mA.
This reduces the resistance of the loop as defined in the relationship below.
In practice, the total loop resistance should not exceed 450 Ω with a voltage >18Vdc
MultiFlame DF-TV7
0V
+24VDC
20 mA loop
Power supply vol
=
R maxi
22
Page 24 / 56
Detector
JP11
Shielding to be
connected to the
enclosure
−
tage 8 V
mA
4 wires Version
NOSP16358-03 [04/2016]