Multichannel Installations - Fisher FIELDVUE DLC3010 Instruction Manual

Installation
October 2014
Test connections inside the terminal box can be used to measure loop current across an internal 1 ohm resistor.
1. Remove the terminal box cap.
2. Adjust the test meter to measure a range of 0.001 to 0.1 volts.
3. Connect the positive lead of the test meter to the + connection and the negative lead to the T connection inside the
terminal box.
4. Measure Loop current as:
Voltage (on test meter)  1000 = milliamps
example:
Test meter Voltage X 1000 = Loop Milliamps
0.004 X1000 = 4.0 milliamperes
0.020 X 1000 = 20.0 milliamperes
5. Remove test leads and replace the terminal box cover.

Multichannel Installations

You can connect several instruments to a single master power supply as shown in figure 2‐12. In this case, the system
may be grounded only at the negative power supply terminal. In multichannel installations where several instruments
depend on one power supply, and the loss of all instruments would cause operational problems, consider an
uninterruptible power supply or a back‐up battery. The diodes shown in figure 2‐12 prevent unwanted charging or
discharging of the back‐up battery. If several loops are connected in parallel, make sure the net loop impedance does
not reach levels that would prevent communication.
Figure 2‐12. Multichannel Installations
+
+
Instrument
No. 1
- -
+
Instrument
No. 2
-
E0364
Note that to provide a 4‐20 mA analog output signal, the DLC3010 must use HART polling address 0. Therefore, if a
multichannel installation is used with all transmitters in 4‐20 mA output mode, some means must be provided to
isolate an individual transmitter for configuration or diagnostic purposes. A multichannel installation is most useful if
the instruments are also in multi‐drop mode and all signaling is done by digital polling.
24
R
Lead
R
Lead
Device No. 1
R
Lead
R
Lead
Device No. 2
230 and 1100 W
if no Load Resistor
Readout
Battery
Backup
Readout
To Additional
Between
Instruments
Instruction Manual
D102748X012
+
+
DC Power
Supply
-
-