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.

Indication	Steady On	Steady Off	Blinking

Indication	Steady On	Steady Off	Blinking
Power	Correct Function	Fault	Fault
TX	Fault	No data traffic	RS232 Data Observed on the Transmit line
RX	Fault	No data traffic	RS232 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 Connection	Notes

	Safety Critical Equipment Connection	Notes
1	No Connection
2	No Connection
3	No Connection
4	No Connection
5	RS232 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.
6	RS232 TX Line
7	RS232 GND Line
8	No Connection

	Data Acquisition Equipment Connection	Notes

	Data Acquisition Equipment Connection	Notes
1	RS485 "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.
2	RS485 "TX" data-stream B Connection
3	RS485 "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.
4	RS485 "RX" data-stream B Connection
5	No Connection
6	No 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

Electrical
Serial Input	1 x RS232 Full-Duplex 3-Wire Input
Serial Output	2 x RS485 Half-Duplex 2-Wire Output
Baud Rate	57,600 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
Indications	Power, TX Active, RX Active

Mechanical

Mechanical
Length	102 mm
Width	22.5 mm
Height	82 mm
Weight	80 g
Mounting	DIN Rail

Environmental Ratings

Environmental Ratings
IP Rating	4X
IK Rating	06
Temperature Range	-25 to +85 °C
Flammability	UL94-V0