SDX-RTX Remote Transmitter (Wall Mounted) – Shire Controls

01279 434399

SDX-RTX Remote Transmitter (Wall Mounted)

Class 1 Medical Device: Medical Gas Pipeline Systems
For more information & documentation please Contact us.

The SDX-RTX transmitter links to the SDX-15 Alarm system via 2-core data bus cable.
4no input signals are wired from each gas (plant or manifold), via an end-of-line termination board, knowns as a TB4 PCB (optional).
Each gas requires upto a 5-core cable (4no switched conditions and 1no Common) and up to 4no gases can be in-putted via 1no SDX-RTX

Transmitter PCB requires a 230vac supply.
All supply, input and data-bus terminations are via simple 45deg PCB mounted terminals.

The SDX-RTX is manufactured in a 1, 2, 3 or 4 channel (gas) variation, to suit the customers needs.
These transmitters can also be upgraded to add or delete channels without the need to re-install new/additional enclosures and supplies.

The transmitter incorporates a single channel selector switch which determines the transmitted channel for the first gas (marked on the PCB as Service A). Where additional gases are required, the SDX-RTX will transmit as follows:

Service A – Transmitted on channel selected by rotary switch (channel always used)
Service B – Transmitted on channel selected by rotary switch plus 1, (used on one and two gas variations only)
Service C – Transmitted on channel selected by rotary switch plus 2, (used on one, two and three gas variations only)
Service D – Transmitted on channel selected by rotary switch plus 3, (used on four gas variation only)

The SDX-RTX transmitter receives 4no analogue signals from up to 4no gases (plant or manifold) and then transmits these signals via a 2-core data-bus using Shire Controls own Medcon signal protocol. A single 2-core data-bus can transmit up to 60 status conditions (15no gases, each with up to 4no condition) and channels are determined via hexadecimal (16 way) rotary switches for transmitting (via SDX-15 transmitters) and receiving for display purposes (via SDX-15 Plant Alarms) or for interfacing to others (via SDX Computer Interfaces).

For monitoring of input signal wiring, a termination box is required to be mounted as close as practical to the gas source. The integrity of the cabling between the gas source and the SDX-RTX is monitored, and a fault on this cable will result in visual system fault warning, with all affected alarm conditions going into alarm condition.

Monitoring of the data-bus connection is always in operation. The transmitter looks to receive a strobe signal from the designated ‘Central Panel’ (the 24-hour monitored SDX-15 Plant Alarm), which ensures the system data-bus integrity. Any short-circuit, open-circuit or non-presence of a Central Panel will result in the transmitter giving a visual warning of this system fault.

As the system is addressable, ALL SDX-15 system equipment (Alarms, Transmitters and Interfaces) can be added/removed or relocated within the system. This simply requires the 2-core data-bus to be extended from the nearest existing SDX-15 Unit, or tee-ing off from a nearby existing cable run. Use 2-core screened cable (minimum 0.5mm).

PCB LED Indicators:
SDX-RTX has 3 5mm round LED indicators – Green, Yellow and Red:

  • Green – This LED shows that the 8vdc control voltage is present on the PCB. In order for this LED to be ON, the following are OK:
    Both the glass 315ma and 230vac 250ma ceramic fuses.
    PCB transformer and rectifier circuit.
    230vac is present.
  • Red – This LED will be OFF if the system is functioning. The LED will flash if any of these occur:
    There is a short circuit anywhere on the 2-core data-bus cable.
    There is an open-circuit on the 2-core data bus cable between the designated ‘Central Panel’ and the SDX-RTX Transmitter.
    The designated ‘Central Panel’ has been switched off (i.e. has neither power nor battery back-up operating).
    The designated ‘Central Panel’ has is set-up as a ‘Repeater’ or the Control PCB has been unplugged.
  • Yellow – This LED will be off if the system is functioning. The LED will flash if any unused input connections are NOT linked out to common via a 56K or 1K8 0.25watt resistor.

Installation requirements:
A 230 vac supply, fused at 3 amps, fed from the essential supply
A 2-core screened cable (minimum 0.5mm) to SDX-15 data-bus.
A 5-core screened cable from each input gas connected (max. 4 gases).
All screens to be earthed at BOTH ends.

Equipment Warranty:
Warranty: alarms returned to our works which have failed due to faulty parts or manufacture will be repaired (or replaced) without charges for parts and labour.
10 year compatibility warranty: Install the SDX Plant Alarm System with the confidence that equipment will be available to modify or extend the system for at least 10 years.

HTM 02-01 compliant

Part Numbers:
When ordering, please specify the following format:


x = number of gases (1,2,3 or 4)
If possible, the hospital in which the alarm is to be installed.


SDX-RTX (All Gases) Surface Box Dimensions 255mm200mm100mm
SDX-RTX (All Gases) PCB Only Dimensions180mm140mm45mm


Can I switch off a channel on my transmitter?

Yes. If you need to disable (turn off) one off you transmitted channels there are two ways of doing this:

1) Link out all of the inputs on the unwanted channel, 1, 2, 3 & 4 to common with a 1K8 0.25watt resistor (colours - brown, grey, red, gold). Using this value resistor will enable the transmitter to operate without generating a system fault (flashing yellow LED), but will also allow the gas fault conditions to be switched - thus leaving the channel free for use at this transmitter or from a new one.

If you do not have these resistors available, simply connect the unwanted channel to a TB4 PCB using a 5-core link and leave the 'To Plant' side of the TB4 disconnected.

2) The transmitter is populated from left-to right depending on how many gas inputs are required. If one channel is to be switched off, this can be done by changing the red jumper links to the right of the channel selector switch. There are 6 rows of 2 pins, which are either linked top-to-bottom with these red links or are left empty. The set up is as follows - using the first two sets of pins on the left hand side (i.e. nearest the rotary channel selector switch):

For One Gas Operation on Service A
Pin Set 1 - Empty
Pin Set 2 - Empty

For Two Gas Operation on Service A & B
Pin Set 1 - Linked
Pin Set 2 - Empty

For Three Gas Operation on Service A, B & C
Pin Set 1 - Empty
Pin Set 2 - Linked

For Four Gas Operation on Service A, B, C & D
Pin Set 1 - Linked
Pin Set 2 - Linked

Order Form