Panametrics HydroProII, User Manual

Page: 25 / 104

HygroPro
II
User's Manual 13
Chapter 1. Installation
1.4.2.4 Requirements for External Devices
When connecting the HygroPro
II
to external devices, the allowable total load capacitance and inductance for those
devices are listed in the manufacturer’s datasheets. The entity parameters of the external devices (e.g. voltage,
current and power) must be equal to or lower than the same specifications for the HygroPro
II
.
The entity parameters for the HygroPro
II
are listed in Table 5 below.
1.4.2.5 Specific Conditions for Use
The HygroPro
II
has hazardous area certifications for ATEX (FM22ATEX0011X, FM22ATEX0013X), UKCA (FM22UKEX0011X,
FM22UKEX0014X), IECEx (IECEx FMG22.0008X), U.S. (FM22US0016X) and Canada (FM22CA0011X). The “X” at the end of
these certificate numbers indicates that special conditions are required for safe operation, which include:
1. The equipment must be used with linear Zener barriers or galvanic isolators.
Following the same special conditions listed above is recommended for regions outside of Europe as well.
1.5 HART Communications
The HART protocol is an open industry standard maintained by the FieldComm Group that makes use of the
Frequency Shift Keying (FSK) standard to superimpose digital communication signals at a low level on top of the
4-20 mA analog output. This enables two-way field communication to take place between one or more HART
masters and intelligent field transmitters such as the HygroPro
II
. Superimposing digital signals on the analog output
makes it possible for additional diagnostic information beyond just the normal process variable to be
communicated with a smart field instrument. The HygroPro
II
is compatible with HART® 7.0 protocol. Hart 7.0 is
compatible with earlier versions of the HART protocol. The device supports both Multi-drop and point-to-point
communication technology.
1.5.1 HART Connection Point to Point
HART technology is a master/slave protocol, which means that a smart field (slave) device only speaks when spoken
to by a master. The HART protocol can be used in various modes such as point-to-point or multi-drop for
communicating information to/from smart field instruments and central control or monitoring systems. The HART
Protocol provides for up to two masters (primary and secondary) as shown in Figure 5 above. This allows secondary
masters, such as handheld communicators to be used, without interfering with communications to/from the primary
master, i.e., control/monitoring system.
Table 5: HygroPro
II
Entity Parameters
Loop Power Supply
U
i
= 28 V P
i
= 0.7 W L
i
= 0 µH
I
i
= 100 mA C
i
= 0 µF
RS485 Digital Output
U
i
= 4.0 V P
i
= 250 mW L
i
= 0 µH
I
i
= 250 mA C
i
= 0 µF
WARNING!
Never connect or disconnect the HygroPro
II
in the hazardous area when supply power or
the communication circuit is energized. Isolate the supply lines in the non-hazardous
area first.