ACARS CMU Simulator
The SPCI CMU Simulator replaces the ACARS Communications Management Unit for end-to-end testing of the ACARS system. It communicates with an Inmarsat Classic Aero or SB-Safety Satellite Data Unit (SDU) via ARINC-429 to generate and receive ACARS traffic.
The CMU Simulator is implemented as a Physical Layer Tester script, and can run on either a BPLT or a GDU. In addition, it can run on a standard PC using a special version of the GDU or BPLT software. In all cases, a suitable ARINC-429 interface must be present.
For local testing, a GDU hosting the CMU Simulator can also run the GES Emulator facility to act as the ground side of the ACARS network (see Local Operation under CMU Simulator Configuration). In this case the ACARS messages sent by the CMU Simulator are displayed in the Link Service User window of the GES Emulator. Uplink messages can also be sent to the CMU Simulator from this window.
The CMU Simulator provides flexible control over the content and timing of the ACARS messages sent. Messages can be entered interactively or read from files, and can be sent individually or periodically at a specified rate. Traffic statistics are calculated, and the messages sent and received are logged.
The Aircraft Communications Addressing and Reporting System (ACARS)
The Aircraft Communications Addressing and Reporting System (ACARS) allows text messages to be communicated between aircraft and ground systems for air traffic control, aeronautical operational control, and airline administrative control
The airborne equipment consists of an ACARS Management Unit (MU) or a Communications Management Unit (CMU) operating as an ACARS MU. The MU or CMU can be connected to ancillary equipment such as the Flight Management System (FMS), Digital Flight Data Acquisition Unit (DFDAU), or cockpit printer.
ACARS messages are transmitted over one of three air-ground subnetworks: HF, VHF, or Satcom. The router function built into the MU/CMU determines which subnetwork to use when routing a message from the aircraft to the ground. The airline operator provides a routing table that the CMU uses to select the best subnetwork.
The Satcom interface provides a satellite-based data link capability. To access the Satcom subnetwork, the ACARS CMU is connected to the Satellite Data Unit (SDU) by a pair of ARINC-429 data buses.
| Configurable Parameters | |
|---|---|
| Functions |
|
| Downlink |
|
| MSN | Automatic or manual MSN selection MSN pool for automatic selection MSN for manual selection |
| Terminator | ETX or ETB |
| BCS validity | Correct or incorrect |
| Message text | Automatically generated, manually specified, or read from file Max and min length for automatic generation |
| Downlink blocks | Number to send, or total duration Interval |
| Ack | Automatic or manual Ack of uplinks Use last received or manually specified UBI for Ack of uplink Timeout for Ack of downlink |
| Link setup | Automatic or manual link setup Automatic or manual media advisory |
| Logging enable | ACARS blocks sent ACARS blocks received ARINC labels sent ARINC labels received |
| Statistics | Blocks sent/received Acks sent/received/missed Max/min/avg Ack latency |
| Status | CMU state SDU state GES ID Sat ID Service type Last DBI sent Last UBI received Last MEN sent |
| Host platform | BPLT, GDU, or PC with BSCR software |
| ARINC-429 interface | Abaco CEI 520A, RCEI-530, or RAR-USB |
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Ottawa, ON, Canada K2K 2A3
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