MHY 925
MHY 925
Multi-fold input/output element with isolator
MHY 925 is an addressable multi-fold element containing 8 (4) programmable inputs and 8 (4) programmable outputs.

MHY 925 is an addressable multi-fold element containing 8 (4) programmable inputs and 8 (4) programmable outputs. It connects to a detection loop of analogue addressable
control panels LITES, and when supplemented with appropriate module also to SL-RS 485 communication line of control panels MHU 115 and MHU 116/117. The element contains
an isolator.

Inputs serve for automatic signalling of pre-defined exceptional states of any external device, which signals this state by either closing or opening an electronic contact, or by voltage applied to opto-isolated input. Inputs can also be set as monitored.

Outputs serve for controlling of external devices connected to device’s switch-over NO/NC contacts.

MHY 925 comes in two types:
a) MHY 925/4 – contains 4 programmable inputs and 4 programmable outputs
b) MHY 925/8 – contains 8 programmable inputs and 8 programmable outputs

Input/output element MHY 925 can be connected to a detection loops of control panels MHU 110, MHU 111, MHU 115, MHU 116 and MHU 117. After adding the DLS 925 communication module the MHY 925 can be connected to SL-RS 485 communication line of control panels MHU 115, MHU 116 and MHU 117.

Properties of each input and conditions of outputs activation are defined in configuration program for control panels.

Electronic circuits of element MHY 925 are on a PCB that is placed in a plastic box with removable cover. Communication module DLS 925 connects to a connector and is secured with spacers on the PCB.

Working principle

The element is powered by impulse voltage from detection line of control panel, or if connected to communication line SL-RS 485, from control panel’s source or from external backup power supply. Input lines can be connected as opto-isolated, or as closing/opening contact. These inputs can also be set as monitored, where the opening contact (fault) and closing contact (fire alarm) of the connected external device can be connected simultaneously. At the same time the input lines are monitored for interruption and short-circuit.

Outputs are bistable relays with switch-over potential-free contacts.

The addressable part registers the control panel’s communication, reports own address and sends information when input is activated or activates own output.


Working conditions
The element is designed for environments protected against weather conditions with classification of conditions according to ČSN EN 60721-3-3.
K: climatic conditions for the environment 3K5
- working temperature range  (from -25 to +70) °C
- relative air humidity range  max. 95 % at +40 °C
- atmospheric pressure range (from 86 to 106) kPa
- without condensation, icing and ice formation  
Z: special conditions 3Z1 heat radiation negligible
B: biological conditions 3B1 without presence of flora and fauna
C: chemical active substances 3C1
S: mechanical active substances 3S1
M: mechanical conditions 3M1
Lasting of significant temperature (45 – 70)°C 2 months/year
Lasting of significant humidity (85% – 95%/≤ 40°C) 100 hours/year


Technical parameters
Power supply from detection loop:
Power supply (18 ÷ 21) Vimp
Normal state current (to add to loop current) max. 200 μA
Power supply from SL-RS 485:
Power supply (19 ÷ 28) V
Consumption with module DSL 925 max. 20 mA
Number of outputs 4 or 8
Input opto-isolated – voltage
input voltage 9 – 30 V (logical 1), 0 – 3V (logical 0)
input resistance cca 10 kΩ
Input contact closing/opening
lines and closed contact resistance max. 1 kΩ
open contact resistance min. 10 kΩ
Input contact monitored
line resistance max. 100 Ω
normal state resistance 10 kΩ
alarm state resistance 4,7 kΩ
element fault resistance 20 kΩ
Number of outputs 4 or 8
Maximal switching current 1 A
Maximal switching voltage 48 V
Maximal switching power 30 Wss> / 40 VAst
Usable for electricity grid no
Optical signalling red and yellow LED
Address adjustment (via MHY 535/536) 1 to 128
Protection according to ČSN 60529 IP 54
Radio screening degree according to ČSN 55022 B-class equipment
Cross-section of connectable wires (0,2 až 1,5) mm2
Dimensions (254 × 180 × 63) mm
Weight approx. 600 g

The MHY 926 is designed for connection to a safe device according to ČSN EN 60950 and meets the requirements of the ČSN EN 54-18 standard for input / output devices.