Yokogawa Multi Channel Oxygen Analyzer System ZR22/AV550G - Manual (Page 6)

<1. OPERATION VIA HART COMMUNICATOR>
1-1
IM 11M12D01-51E
1. Operation via HART Communicator
1.1 Conditions of Communication Line
1.1.1 Interconnection between AV550G and HART Communicator
The HART Communicator can interface with the AV550G from the control room, the AV550G site,
or any other wiring termination point in the loop, provided there is a minimum load resistance of
250Ω between the connection and the receiving instrument. To communicate, it must be connected
in parallel with the AV550G, the connections are non-polarized. Figure 1.1 illustrates the wiring
connections for direct interface at the AV550G site. The HART Communicator can be used for remote
access from any terminal strip as well.
Figure 1.1 Interconnection Diagram
1.1.2 Communication Line Requirements
Specifications for Communication Line:
Load resistance: 250 to 550Ω (including cable resistance)
When multidrop mode, see Figure 1.2.
Minimum cable size: 24 AWG, (0.51 mm diameter)
Cable type: Single pair shielded or multiple pair with overall shield
Maximum twisted-pair length: 2,000 m
Maximum multiple twisted-pair length: 1,000 m
Use the following formula to determine cable length for a specific application;
L= 65 x 10
6
(R x C)
(C
f
+ 10,000)
C
where: L = length in feet or meters
R = resistance in ohms, current sense resistance
C = cable capacitance in pF/ft or pF/m
Cf = 50,000 pF
+
–
4 to 20 mA DC signal line with
superimposed HART AC signal
Control room
Terminal board
Receiving instrument
load resistance:
250Ω to 550Ω
Relaying
terminals
HART
Communicator
Model 275
HART
Communicator
Model 275
HART
Communicator
Model 275
Ave-a +
Ave-a -
F34.ai
AV550G