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HZS232 User Guide

Owned by Mark Beeson (Deactivated)
Last updated: Apr 09, 2019 by Martyn Emmett (Unlicensed)
3 min read

Use Case:

The "HZS232 RS232 to RS485 snooper" facilitates the monitoring of a full-duplex RS232 link in a minimally intrusive and low risk manner.

It is designed primarily for the monitoring of data links in safety critical, high reliability systems, such as Railway Signalling TDM control systems.

Key Features:

  • Separate high impedance, fault tolerant input buffers monitor RS232 transmit and receive lines.
  • Buffered RS232 to RS485 protocol conversion prevents downstream monitoring systems from injecting data into the RS232 line.
  • RS485 output allows long-distance wiring runs, and provides enhanced electromagnetic immunity between HZS232 and monitoring equipment.
  • 1 kV galvanic isolation barrier guards against ground loop problems, unintentional earth paths, or other unwelcome circuit connection.

System Diagram:

Indications

The HZS232 incorporates 3 x Indication LED's to aid the identification of correct operation.

IndicationSteady OnSteady OffBlinking
PowerCorrect FunctionFaultFault
TXFaultNo data trafficRS232 Data Observed on the Transmit line
RXFaultNo data trafficRS232 Data Observed on the Receive line

Wire Termination

  • Wire termination is via 5 mm-pitch 8-way connectors.
  • The connector assignment has been arranged such that the monitored system shall not be compromised if the plug is inserted into the incorrect socket of the HZS232.
  • The correct terminations are clearly marked on the product.
  • Reading from left-to-right, the correct pin assignment is further detailed below:

Safety Critical Equipment ConnectionNotes
1No Connection
2No Connection
3No Connection
4No Connection
5RS232 RX Line
  • RS232 connections are device "inputs".
  • The HZS232 "Observes" RS232 traffic on the TX and RX lines.
  • It is not possible to inject data onto the RS232 lines.
  • Inputs are high-impedance.
  • Inputs are galvanically isolated from the RS485 outputs.
6RS232 TX Line
7RS232 GND Line
8No Connection

Data Acquisition Equipment ConnectionNotes
1RS485 "TX" data-stream A Connection
  • RS485 connections are device "outputs".
  • Traffic on the RS232 Transmit line is re-transmitted on this RS485 pair.
  • The output baud rate matches the input baud rate.
2RS485 "TX" data-stream B Connection
3RS485 "RX" data-stream A Connection
  • RS485 connections are device "outputs".
  • Traffic on the RS232 Receive line is re-transmitted on this RS485 pair.
  • The output baud rate matches the input baud rate.
4RS485 "RX" data-stream B Connection
5No Connection
6No Connection
7

-Power

  • Wide input power 9V to 30V DC.
  • Polarity protection provided.
8+ Power

A Note about Cable Terminations

Correct selection of cable type and termination method to safety critical systems is beyond the scope of this user guide

  • Please ensure the cabling used to connect to safety critical systems is of the correct type and carries the correct approvals.
  • Please ensure that the appropriate termination method is employed.
    • Common "Punch-Down-Blocks" require the use of solid-conductor cable and the use of appropriate termination tools.
    • Common D9 connectors may use multi-stranded cable, but require the pin assignment of the plug to be carefully checked.

Specification

 Electrical 
Serial Input1 x RS232 Full-Duplex 3-Wire Input
Serial Output

2 x RS485 Half-Duplex 2-Wire Output

Baud Rate57,600 bps max.
Input Impedance

> 1 MΩ on both RS232 TX and RX Lines

Power Supply

9 V to 30 V DC

Power Consumption

0.5 W at 12 V DC

0.6 W at 24 V DC

Isolation> 4 MΩ at 1,000 V DC
IndicationsPower, TX Active, RX Active
Mechanical
Length102 mm
Width22.5 mm
Height82 mm
Weight80 g
MountingDIN Rail
Environmental Ratings 
IP Rating4X
IK Rating06
Temperature Range-25 to +85 °C
FlammabilityUL94-V0