C135 PCS 7 (PCS7)
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Integration of SCALANCE M Cellular Routers in PCS 7 for SMS Alarm Notification and Remote Telecontrol

Integration of SCALANCE M Cellular Routers in PCS 7 for SMS Alarm Notification and Remote Telecontrol

SCALANCE M industrial cellular routers (such as M874-2, M874-3, and M876-4 LTE) are not included in the standard SIMATIC PCS 7 Released Modules catalog ('Freigegebene Baugruppen') as plant bus switches, but they are fully supported as external security/telecontrol communication routers. For automated SMS alarm notification during plant fault conditions, three primary architectures exist: 1) Deploy the official PCS 7 add-on AlarmControl Center (ACC), which interfaces with SCALANCE M or GSM modems; 2) Utilize WinCC Global Scripts (C or VBS) to send automated HTTP GET/POST API commands or AT commands directly to the SCALANCE M router to dispatch SMS messages; or 3) Integrate remote field stations via PCS 7 TeleControl using SINAUT ST7, DNP3, or IEC 60870-5-104 protocols over the cellular link.

Table of Contents

Executive Summary

In distributed water/wastewater, oil and gas, and remote utility installations automated with SIMATIC PCS 7, plant operations frequently mandate automated SMS alert dispatches to on-call maintenance personnel whenever critical alarms or emergency trips occur. Engineers evaluating hardware often question whether Siemens SCALANCE M-series industrial cellular routers (e.g., M874 and M876) are compatible with PCS 7. While these devices are not plant bus Ethernet switches, they are proven industrial communication appliances. This technical guide outlines the compatibility boundary of the SCALANCE M family within PCS 7, details how to trigger SMS dispatches programmatically from WinCC OS, and evaluates the official SIMATIC PCS 7 TeleControl and AlarmControl Center options.

Architecture and Fundamental Mechanics

SCALANCE M Cellular Router Integration Architectures in PCS 7

+-------------------------------------------------------------------------+
|                        SIMATIC PCS 7 OS Server                          |
|                                                                         |
|   [Alarm Logging Event: High Boiler Pressure Trip]                      |
|                                   |                                     |
|         +-------------------------+-------------------------+           |
|         |                                                   |           |
|         v Approach 1: Script API                            v Approach 2|
|   [WinCC C-Script / VBS]                               [AlarmControl   |
|   HTTP POST request to Router                           Center (ACC)]   |
+---------|---------------------------------------------------|-----------+
          |                                                   |
          | Industrial Ethernet (Terminal Bus / DMZ)          |
          v                                                   v
+-------------------------------------------------------------------------+
|                 SCALANCE M Industrial Cellular Router                   |
|                 (SCALANCE M874 / M876-4 LTE)                            |
|                                                                         |
|   - Embedded SMS Service Engine (HTTP API / AT Command Parser)          |
|   - IPsec / OpenVPN Secure Tunneling                                    |
|   - SIM Card Interface (4G LTE / UMTS)                                  |
+-------------------------------------------------------------------------+
                                    |
                                    v Cellular GSM / LTE Air Interface
+-------------------------------------------------------------------------+
|                       On-Call Operator Smartphone                       |
|               SMS: 'ALARM: Boiler 1 Pressure > 85.0 bar'                |
+-------------------------------------------------------------------------+

Integration Approaches Evaluated

  1. SCALANCE M Embedded SMS HTTP API:
    - SCALANCE M routers feature an integrated web server and REST/HTTP API capable of dispatching SMS text messages when receiving a formatted HTTP request from an authorized IP.
    - A lightweight WinCC C-Action or VBS Global Script triggered by the WinCC Alarm Logging GMsgFunction sends an HTTP string containing the recipient phone number and alarm message text.
  2. AlarmControl Center (ACC) - Siemens Approved Add-on:
    - For enterprise-grade paging, escalation workflows, duty rosters, and bidirectional acknowledgement, Siemens markets the PCS 7 add-on AlarmControl Center.
    - ACC connects directly to WinCC Alarm Logging via OLE-DB and drives industrial modems or cellular routers via network sockets.
  3. PCS 7 TeleControl (Remote RTUs):
    - Used when remote wellheads or pumping stations communicate back to the central PCS 7 plant using SINAUT ST7, DNP3, or IEC 60870-5-104 protocols tunneled over VPN via SCALANCE M routers.

Step-by-Step Implementation Procedure

Step 1: Network Placement and SCALANCE M Configuration

  1. Mount the SCALANCE M router on DIN rail and connect its Ethernet LAN port to the plant's Terminal Bus or a secure DMZ network segment. (Never connect directly to the deterministic Plant Bus).
  2. Insert a commercial industrial SIM card with SMS and data capabilities.
  3. Access the SCALANCE M Web Based Management (WBM) via its default IP (e.g., 192.168.1.1).
  4. Configure the cellular APN and confirm registration with the cellular provider.
  5. In WBM, navigate to Services > SMS and enable the SMS service.
  6. Configure user authentication and permit HTTP SMS trigger requests from the specific IP address of the WinCC OS Server.

Step 2: Implement SMS Triggering in WinCC OS via VBScript

  1. In WinCC Explorer, open Global Script VBS.
  2. Create a project function Send_SMS_Alert(strPhone, strMsg):
    vbscript Sub Send_SMS_Alert(strPhone, strMsg) Dim http, url Set http = CreateObject("MSXML2.ServerXMLHTTP.6.0") url = "http://192.168.1.100/api/sms/send?to=" & strPhone & "&text=" & strMsg http.Open "GET", url, False, "api_user", "router_password" http.Send Set http = Nothing End Sub
  3. In WinCC Alarm Logging, attach this function to critical message classes (e.g., Emergency Trip or High Priority Alarm) using the standard GMsgFunction or an event-triggered action.

Step 3: Integrating via AlarmControl Center (Alternative Enterprise Approach)

  1. If duty scheduling, message acknowledgement, and call escalation are required, install AlarmControl Center (ACC) on the OS Server.
  2. In ACC Configurator, establish a communication channel to the SCALANCE M router via network IP and port.
  3. Configure recipient groups, phone numbers, and on-call calendars.
  4. Map WinCC alarm classes directly into ACC alarm criteria.
  5. Note: Validate required ACC licenses and part numbers through an authorized Siemens distributor or the Siemens Industry Mall.

Verification

  1. Manual Router SMS Test: In the SCALANCE M WBM interface under Services > SMS, enter a test mobile number and click Send Test SMS. Confirm receipt on the target smartphone.
  2. WinCC Script Test: In WinCC Graphics Designer, place a temporary button calling Send_SMS_Alert("+1234567890", "PCS 7 Test Alarm"). Click the button in Runtime and verify that the SMS arrives within 15 seconds.
  3. Simulated Trip Verification: Force a simulated high alarm on a process variable in CFC. Confirm that WinCC Alarm Logging generates the alarm event and automatically triggers the script to dispatch the alert.

Limitations and Operational Precautions

  1. Cellular Signal and Network Latency: SMS is a non-deterministic carrier service with no guaranteed delivery time. Critical safety functions must rely on hardwired field interlocks and Safety F-Systems, never SMS.
  2. Plant Bus Isolation: SCALANCE M cellular routers must never bridge external internet/cellular traffic directly onto the PCS 7 Plant Bus (AS-OS communication layer). Always deploy routers within a dedicated DMZ or perimeter firewall.

Engineer FAQ

Are SCALANCE M routers officially listed in PCS 7 Released Modules?

No. The PCS 7 Released Modules list covers plant bus switches (SCALANCE X-series) and controllers; SCALANCE M is treated as an external telecontrol/network accessory.

Can SCALANCE M send SMS alarms directly without a PC?

The router cannot interpret PCS 7 alarms on its own; it requires a trigger from WinCC scripting, an external application (like ACC), or a digital input signal.

What is AlarmControl Center (ACC)?

ACC is an officially endorsed Siemens add-on software for automated alarm notification via SMS, voice call, email, and mobile apps.

Does sending SMS from WinCC require special software licenses?

Custom HTTP/VBS scripts sending SMS via the router require no additional licenses; deploying AlarmControl Center requires an ACC software license.

What SCALANCE models support LTE cellular?

SCALANCE M876-4 and SCALANCE MUM856-1 support 4G LTE and 5G cellular communication.

Can operators acknowledge alarms by replying to the SMS?

Replying to acknowledge alarms requires two-way communication software such as AlarmControl Center; simple HTTP scripts are one-way.

Where should the SCALANCE M router be connected?

Connect the router to the Terminal Bus or an isolated DMZ network segment, never directly to the AS-OS Plant Bus.

Can SCALANCE M be used for remote engineering access?

Yes, SCALANCE M routers support secure IPsec and OpenVPN tunnels for remote engineering via SINEMA Remote Connect.

What protocol is used for remote pumping stations in PCS 7?

PCS 7 TeleControl supports DNP3, IEC 60870-5-104, and SINAUT ST7 communication over cellular VPN links.

What happens if the SIM card loses cellular connectivity?

The router logs a connection failure event; script attempts will time out, which should be caught and logged by WinCC error handlers.

Technical References

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Related Tags

  • SCALANCE M
  • SMS Notification
  • TeleControl
  • AlarmControl Center
  • WinCC Scripting
  • Remote Access
  • Industrial Cellular
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