Flowserve 3400IQ Digital Positioner - Manual (Page 21)

1
Logix 3400IQ Digital Positioner FCD LGENIM3401-00 – 06/06
flowserve.com
The calculated voltage must be greater than 9 VDC in order to safely support the Logix 3400IQ digital
positioner.
Example:
DCS Compliance Voltage = 19 VDC
R
barrier
= 300 Ω
R
wire
= 25 Ω
Current
max
= 23 mA
Voltage = 19 VDC – 0.023 A • (300 Ω + 25 Ω) = 11.5 VDC
The voltage 11.5 VDC is greater than the required 9.0 VDC; therefore, this system will support the
Logix 3400IQ
digital positioner.
Figure 7: Compliance Voltage
+
-
R
barrier
(if present) R
wire
FF
Signal
Source
Compliance
Voltage
Logix
3400IQ
Current
23 mA
9 VDC min
6.4 Cable Requirements
The Logix 3400IQ digital positioner utilizes the FF protocol. This communication signal is superim-
posed on the supply voltage.
FF rated cable should be used. Refer to H1 wiring specification.
6.5 Intrinsically Safe Barriers
When selecting an intrinsically safe barrier, make sure the barrier is FF compatible. Although the
barrier will pass the segment voltage and allow normal positioner operation, if not compatible, it may
prevent FF communication.
6.6 DD Support
The DD for the Logix 3400IQ can be downloaded from either the flowserve website: www.flowserve.
com or the F
oundation
Fieldbus website: www.Fieldbus.org.