DRAFT - 11 December 2014
DRAFT - 11 December 2014
10
DRAFT - 11 December 2014
INM MTL4850_54 Rev4
4.3 HCU16 HART connection unit
The HCU16 HART connection unit - see Figures 4.6 & 4.7 - 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.
Each channel has three terminals: +ve, -ve and a transmitter supply terminal (Tx +) – see Figure
4.6. The HART signal has to be terminated with an impedance of approximately 240
W
. Positions
are provided on the circuit board to fit parallel resistors (normally 250
W
), or an appropriate
series resistor to raise the impedance if it is < 240
W
. This unit can be used with analogue outputs
if the system's current signal is compatible with HART communications.
Connections to the field signals and the system are via screw-clamp terminals.
4.3.1
Mounting
The HCU16 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.
Carrier weight:
330g
Footprint dimensions: See Figure 4.6
Height:
53mm from top of DIN rail
4.3.2
Ribbon cable connector
A 20-way ribbon cable connector is provided on the HCU16 to link to the HMP-HM64.
Figure 4.6
HCU16
connection unit