Product Description
The MSM281A is a five (5) channel, alternate / momentary action controller. It provides five (5) separate circuits configurable as toggle/alternate action or momentary with set/reset capabilities for each circuit. Each relay can control AC or DC devices up to five (5) amperes, MAXIMUM. The circuit logic provides permanent last state memory and momentary switch inputs. This unit can be used in any switch system environment.
Features
The following list provides an overview of features for the
MSM281A: q
Lightweight, compact size q
Solid state circuitry q
Five (5) independent circuits q
Configurable as an alternate action relay q
Configurable as a momentary action relay q
Each channel configured with a set and reset input q
Permanent last state memory q
Five (5) amperes, MAXIMUM load
Application Notes
1. The MSM281A contains five (5) independent circuits. Each circuit has its own set of logic control circuitry and a relay with normally open, normally closed, common switch input, status output/momentary input, and reset input contacts.
2. The unit can be configured as an alternate action relay. This function is accomplished by using the switch input. The switch input causes the controller to change states each time it receives a ground pulse. When the relay is set, the status output produces a hard ground. When the relay changes states, the status output will float.
3. The unit can be configured as a momentary action relay. This function is accomplished by using the status output/momentary input. When this input goes low, the relay will set. As long as the ground is present, the relay will remain set. When the ground is removed, the relay will relax.
In this configuration, the status output is not used
4. Each channel is configured with a set and reset input. These functions are activated with a ground pulse. A ground pulse on the reset line will cause the relay to relax. Additional pulses on the set or reset lines will not affect the state of the relay.
5. The controller’s circuitry will remember the last state of each channel despite power surges, bus changes, and temporary power outages. The set and reset inputs can be used to force a channel into a particular state on power up if desired.
Installation Guidelines
1. Insure that all connecting wires are 24 AWG, MINIMUM (16 to
18 AWG recommended). Grounds shall be made within 12 inches of the unit.
2. Protect power wires with circuit breakers or fuses located close to the electrical power source bus.
3. The unit shall NOT be mounted to the skin of the aircraft.
4. Ensure that power and ground are applied only where required.
MSM281A
Technical Specifications
Electrical Power
Input signal
Maximum current ratings
Mechanical
Relay Ratings
Dimensions
(l x w x h)
Weight
200 mA @ +28 VDC
+28 VDC Power In
5A AC or DC
(each cannel)
Inductive load currents
NOT to exceed 5A
+24 VDC Coil,
5A 250 VAC,
5A +30 VDC
5.0" x 3.1" x 1.3"
12.7cm x 7.87cm x 3.3cm
0.51 lb / 0.23 kg
Drawings Description
521857 Rev IR MSM281 & MSM281A Outline Drawing
Document # 530094A – Revision History
Level Date Description
IR 4/1998
A 3/2000 Overall Update – ECN # 4738
PROPRIETARY NOTICE
Despite any copyright notice, this data and information disclosed herein contains confidential, proprietary designs owned by Audio International, Incorporated. Neither this data nor the data contained herein shall be reproduced, used, or disclosed to anyone without the written authorization of Audio International, Inc.
Audio International, Inc.
•
7300 Industry Drive, N Little Rock, AR 72117
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Phone 501-955-2929 / Fax 501-955-2988 / www.audiointl.com