Elcon MUX 2700, Instruction Manual

- 15 -

IM-ENG-116/GB

6.3 Supply port

Supply voltage:

24 Vdc (-15%, +25%)

Supply current:

20 Vdc 32 mA

(typical, RS485 quiescent)

24 Vdc 28 mA 

(typical, RS485 quiescent)

30 Vdc 23 mA

(typical, RS485 quiescent)

Protection:

internal fuse, not user-serviceable

6.4 Signal port (HART)

Channel number:

32 signal loops

DC-isolation:

dual-capacitor isolation on each loop

Allowed common mode voltage:

up to 30V

Differential mode clamping:

+/- 5.2V (for transient or AC signals)

Receive signal range:

0.12 Vpp < signal  < 1,5 Vpp

Receive impedance magnitude:

> 5000 

Ω

Carrier Detect levels:

signal > 0.12 Vpp     —   CD asserted     

signal < 0.080 Vpp   —   CD not asserted

Transmit signal amplitude :

200 mV (200 

Ω

 load, typical)

500 mV (500 

Ω

 load, typical)

200 

Ω

 load    —    150 mV < signal < 250 mV

Carrier stop time

< 10 bit time

Device connection type:

DC-isolated bus device

Impedance level type:

High Impedance device

Data link type:

Primary or Secondary Master (configurable)

Field multi-drop support:

available on request

For additional, more detailed HART-related specifications, please refer to the 

HART FSK Physical Layer

Specification Rev.8.0

available from the HART Communication Foundation (HCF_SPEC-54), which the Mux 2700

module is generally compliant with.

Notes :                                                 

• To minimise input capacitors size and to get an higher output signal level, the Hart signal transmit section is based

on a current generation technique. For this reasons, the output signal level is proportional to the external load,
which should not exceed 500 

Ω

 to avoid possible cross-talk or saturation problems.

• The specified transmit-signal amplitude is a DC value measured at the centre of a waveform semi-period.

• To maximise allowed cable length and to avoid noise problems, you should avoid to connect to the MUX HART

low impedence devices < 250 

Ω

. 

6.5 Serial port (RS-485)

Line type:

RS-485, differential pair plus GND

Line speed:

9600 Baud or 19200 Baud

Line topology:

multi-point, master-slave connection

Device type:

slave (up to 31 slave Mux can connected to a single master)

Slave addressing range:

1 to 31 (0 reserved)

Protocol type:

H-Port (HART based)

Master device:

Maintenance Workstation (MW)

Warning !

A suitable RS-232 to RS-485 converter is required to connect the port with a standard PC (see Fig. 6).
As for RS-485 line detailed specifications, please refer to the relevant standard.