Gsm home Security systems

A GSM home alarm system is a wireless home security product. The security  door and window opening sensors, link up to a mobile network. Basically, your GSM home security alarm will communicate with the wider GSM network using a SIM card.

Features

Input Power:

• 12V AC / DC, 1A recommended

System Overview:

The GSM Security System monitors 2 digital inputs, configurable for SHORT (active low) or OPEN (active high) detection. It can trigger alerts via SMS and call and optionally activate a siren output.

Digital Inputs:

• Input 1 and Input 2

• Configurable as:

  • DNO – Normally Open (alert on short/LOW)

  • DNC – Normally Closed (alert on open/HIGH)

Siren Output:

• Relay output to control a siren or buzzer

• Can be enabled/disabled using SMS

SMS Command List:

Example Commands:

• To store number +91 9876543210 as 1st number:
  1STN9876543210

• To arm the system:
  ASS

• To configure Input as Normally Open:
  DNO

• To set alert message for Input 1:
  1SMS=Garage Door Alert

⚙️ System Behavior:

• On Input Trigger:

  • Sends SMS to stored numbers (if enabled)

  • Dials the numbers (up to set rounds)

  • Activates siren (if enabled)

Notes:

• All commands must be sent via SMS from a registered number.

• Avoid special characters in custom SMS messages.

• Always use correct format (no spaces unless required).

  
  

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GSM Security System — Step-by-Step Troubleshooting Guide (Customer)

Short, clear steps your customers can follow when something goes wrong.

Quick checklist (before you start)

• Power: 12 V AC/DC connected.

• BAT ON: short (or press) the BAT ON connector/button to power the unit on.

• SIM: inserted, no SIM-PIN, active SMS/call service, and antenna connected.

• Keep both inputs open (not shorted) while configuring/storing numbers.

LED meanings (read first)

• Network LED

  • 1 s blink → Network NOT connected

  • 1 s ON / 3 s OFF → Network CONNECTED

• Status LED

  • After Network Connected → 1 s blink = READY for commands

  • If status LED is not blinking 1 s (solid or other pattern) → unit is busy (eg. dialing). Do not send commands — wait.

Step-by-step troubleshooting

1) No power / unit won’t turn on

1. Check 12 V supply is present (multimeter).

2. Ensure BAT ON connector is shorted / pressed to switch the unit on.

3. Check fuse, wiring polarity, and connectors.

4. If still dead: try a different 12 V supply. Contact support if unresolved.

2) Network not connecting (Network LED = 1s blink)

1. Reboot the unit (power cycle).

2. Check the SIM: is it inserted correctly and active? Remove & reinsert SIM.

3. Make sure SIM has no PIN code (disable PIN on a phone).

4. Check antenna connection and signal at the installation location. Move unit to better signal if possible.

5. If still no connection, try the SIM in a phone to verify network/SIM status and SMS pack.

3) Unit is connected but commands are ignored

1. Wait until Status LED shows 1 s blink (ready).

2. If the status LED shows busy (eg. during dialing), do not send commands — wait until it returns to 1 s blink.

3. Make sure you send commands from an allowed/registered phone number (if your setup restricts commands).

4. Ensure SMS command text has correct syntax (no extra spaces).

4) Storing mobile numbers — IMPORTANT

Do this only when Status LED = 1 s blink and both inputs are OPEN (not shorted):

1. Disarm the system first: DSS.

2. Ensure inputs are not triggered (physically disconnect sensors or verify open).

3. Send numbers:

   • 1STN<mobile> — store 1st number

   • 2STN<mobile> … 5STN<mobile> — up to 5 numbers

4. Confirm with SPN (shows stored numbers).
   Why this matters: If an input is shorted while you store numbers the device may interpret that as an alarm and start dialing immediately (dummy/partial numbers).

5) System starts dialing unexpectedly after storing numbers

Cause: an input was shorted (triggered) during storage.
Fix:

1. Immediately disarm: DSS.

2. Disable dialing temporarily: DIAL=0.

3. Ensure inputs are open/untriggered, then re-store numbers if needed.

6) No SMS alerts arriving (or no SMS reply)

1. Verify MON (SMS on): MON to enable, MOFF to disable.

2. Check SIM has SMS credit / SMS pack with carrier. (Send a test SMS from the SIM to another phone.)

3. Check 1SMS= / 2SMS= messages are ≤ 20 characters and contain no unsupported characters.

4. Confirm SPN shows correct numbers.

5. If still bad, move unit to better signal or try another SIM.

7) Dialing not happening (no calls)

1. Check DIAL setting:

   • DIAL=0 → dialing OFF

   • DIAL=1 / DIAL=2 / DIAL=3 → dialing rounds (1–3)

2. If calls aren’t happening, send DIAL=2 (force dialing on).

3. If you want to stop dialing immediately, use DIAL=0 or DSS.

4. If only one number is getting called, set how many numbers to call using STN=X (X = 1–5). Example: STN=5 calls/sends SMS to all stored numbers.

8) Device stuck busy or continuous dialing

1. Wait for the Status LED to return to 1 s blink before sending more commands.

2. To stop dialing now: DIAL=0 or disarm DSS.

3. If the unit remains stuck, power cycle the device (turn off, wait 10 s, turn on).

4. As a last resort: remove and reinsert the SIM, then reboot.

Common symptoms → quick fixes

• Power OK, but no network → Reinsert SIM, disable PIN, check antenna, test SIM in phone.

• Commands not accepted → Wait for Status LED (1 s blink), check command formatting.

• Starts calling when storing numbers → Inputs were shorted; disarm & DIAL=0, ensure inputs open, then reconfigure.

• SMS not sent/received → Check SIM SMS credit, MON state, message length, signal level.

• Only 1 number is called → set STN=X (e.g. STN=5 for all).

Commands quick reference

• 1STN<mobile> … 5STN<mobile> — Store numbers 1–5

• SPN — Show stored numbers

• ASS — Arm (System ON)

• DSS — Disarm (System OFF)

• DNO / DNC — Set input type (Normally Open / Normally Closed)

• SEN / SDB — Siren ON / Siren OFF

• MON / MOFF — SMS ON / SMS OFF

• DIAL=0 … DIAL=3 — Disable/Enable dialing (0=off, 1–3 rounds)

• STN=X — Set how many numbers to call/SMS (X = 1 to 5)

• 1SMS=... / 2SMS=... — Custom alert text (max 20 chars each)

Best practices & preventive checks

• Always disarm (DSS) before changing stored numbers or testing.

• Keep the SIM credited with SMS/call balance.

• Test the system after installation: store numbers -> enable MON/SEN -> arm (ASS) -> trigger input -> confirm SMS and calls.

• Keep a note of the exact command formats and avoid extra spaces/special characters.

• Monthly test: verify network LED connected, SPN correct, siren/test alerts work.

If problem persists — support template

When contacting support, give:

• Device model / serial (if any)

• Date & time of the issue

• LED states (Network LED + Status LED patterns) at the time of problem

• SIM number and operator

• Commands you sent and timestamps

• Steps already tried (power cycle, reinsert SIM, DIAL=0, etc.)

Example message to support:

Device: GSM Security v1 — S/N: XXXXX
Issue time: 2025-09-24 11:32 IST
Network LED: 1 s ON / 3 s OFF (connected)
Status LED: continuous (busy) — never returned to 1 s blink
Commands used: SPN, DIAL=0, DSS — no change.
SIM operator: Airtel, test SMS from SIM to phone succeeded.