Instruction manual

5
INM4840-5 Nov 2007
5
4 INSTALLATION
4.1 System overview
See Figures 2.1 and 4.1.
4.2 BPHM64 HART backplane
For medium to large scale installations, the BPHM64 HART backplane
is the method of choice to handle the HART maintenance signals
passing to and from the field devices.
The backplane accommodates 1 x MTL4841 and up to 4 x MTL4842
modules. However, an MTL4841 can support up to 16 x MTL4842
modules and so the system has been designed to expand easily by
interconnecting an additional three BPHM64 backplanes. Note that
the other BPHM64 backplanes only require MTL4842 modules, not
MTL4841 modules (see Figure 4.1).
4.2.1 Mounting
The BPHM64 is designed for mounting in a control room equipment
cabinet and is supplied fitted on a carrier suitable for T or G section
DIN-rail mounting in any orientation.
Weight (excluding modules): 296g
Weight (per module) 100g approx.
Footprint dimensions: See Figure 4.2
Height (modules fitted): 116mm from top of DIN rail
4.2.2 DC power connections
The BPHM64 has a removable, 4-way, screw-clamp terminal
connector that provides redundant 24V dc supply connections.
Power requirements: Voltage: 21–35V dc
Current: 72mA @ 24V dc
Connect the dc power to the board as shown in Figure 4.3.
4.2.3 HART signal connections
Each of the four MTL4842 modules has a DIN41651 20-way ribbon
cable connector (P1–P4) beside it. Each one provides 16 signal
connections and 4 ground returns to the module. These connectors
receive the HART signals coming from either connection units or
backplanes equipped with similar DIN41651 connectors. See Section
4.12 for cabling recommendations and limits. MTL can provide
20-way cables in a range of different lengths on request.
Connect the ribbon cables to the appropriate connector for the
corresponding MTL4842 module.
4.2.4 Link to other BPHM64 backplanes
Up to four boards may be linked together to provide a total of
sixteen MTL4842 modules under one MTL4841 communications
module (see Figure 4.1). 10-way connectors P5 and P6 (Figure 4.2)
are used to link the additional BPHM64 backplanes together.
See Section 4.12 for cabling recommendations and limits. MTL can
provide 10-way cables in a range of different lengths on request.
4.2.5 MTL48xx modules fitting and configuration
MTL4842 modules may be fitted in any position that corresponds with
a HART signal cable. See Section 5 for details.
4.2.6 RS485 communication connections
Two RS485 ports are provided on the board - see Figure 4.2.
These are used to connect the BPHM64 backplane to the PC
running the maintenance software and to onward link to MTL4841
communications modules on other backplanes.
Full details of this communications link are provided in Sections
4.12.3 and 4.12.4.
4.3 HCU16 HART connection unit
The HCU16 HART connection unit - see Figures 4.4 & 4.5 - provides
a connection interface between the field wiring and the onward link
to the host/system control for non-hazardous areas. It also provides a
take-off point for the HART signals to the maintenance system.
Connections to the field signals and the system are via screw-clamp
terminals and the link to the BPHM64 is via a 20-way ribbon cable.
Each channel has three terminals: +ve, -ve and a transmitter supply
terminal (Tx +) – see Figure 4.5. The HART signal has to be terminated
with an impedance of approximately 240Ω. Positions are provided
on the circuit board to fit parallel resistors (normally 250Ω), or an
appropriate series resistor to raise the impedance if it is < 240Ω. This
unit can be used with analogue outputs if the system's current signal
is compatible with HART communications.
The HCU16 is supplied fitted in a carrier for DIN rail mounting. The
footprint of the carrier is 150 x 125mm and the height from the top
face of T-section DIN rail is approximately 55mm.
125 mm
150 mm
BPHM64
HART
INTERFACE
Tx2+
Ch2+
Ch2-
Ch1-
Ch1+
Tx1+
Ch1-
Ch1+
Tx1+
Tx2+
Ch2-
Ch2+
HCU16
15
13
11
9
1
7
3
5
16
14
12
10
2
8
4
6
15
13
11
9
1
7
3
5
16
14
12
10
2
8
4
6
SYSTEM
FIELD
P1
MTL4842 MTL4842 MTL4842 MTL4842 MTL4841
PWR1
PWR2
P1 P2 P3 P4
PORT1 PORT2
P6
P5
BPHM64
0V
PWR
1 2
FS1
HART
signal
connections
Links to
additional
BPHM64
backplanes
DC
supply in
RS485
ports to
management
system
MTL4841
MTL4842s
206 mm
125 mm
Figure 4.2 - BPHM64 - backplane
Figure 4.4 - HCU16 connection unit
PWR 1
0V
PWR 20V
Figure 4.3 - DC power connections