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Appendix 2.6 to ETSO-C153a - Integrated Modular Avionics (IMA) Module Minimum Performance Standard (MPS)

Available versions for ERULES-1963177438-18129

ED Decision 2020/011/R found in: CS-ETSO Amdt 17 - European Technical Standard Orders (Oct 2026)

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**Appendix
2.6 to ETSO-C153a – Integrated Modular Avionics (IMA) Module
Minimum Performance Standard (MPS)**

*ED
Decision
2020/011/R*

**CLASS IF: Interface**

**1. Purpose
and scope**

1.1. Introduction

This Appendix contains the Minimum Performance Standards (MPS) for
the CLASS IF Intended Function: Interface.

These standards specify characteristics that should be useful to
designers, manufacturers, installers and users of the IMA module.

1.2. Definitions

For ETSO-C153a CLASS IF, the IMA module provides shared resources in
terms of interfaces between hosted applications, modules and/or
components.

The following definitions are used:

—
Interface Unit: a set of hardware
and/or software components in charge of supplying and managing a
shared information resource.

—
Data Thread: a well-defined set of
data which is a primary form of information and for which a level of
isolation would be guaranteed by the IMA module.

Each data thread handled by the Interface, if so wished by the
applicant, may be bidirectional or symmetrical between interconnected
components, modules, or hosted applications.

In the context of IF class, the ‘concurrent item’ defined in
Appendix 2.1, paragraph 1 means ‘Data Thread’.

1.3. Intended Function

For ETSO-C153a CLASS IF, the intended function is to provide the
capability to share information supplied by one or several interfaces
units.

This intended function is Information Sharing composed of:

—
information acquisition and
control;

—
information conversion and; and

—
information forwarding and control.

The information-forwarding and control function is the means that
allows sharing information between components, modules and/or hosted
applications.

The following figure provides an overview of the above-mentioned
intended function and the associated definitions:

![](/static/files/file_jytjXw2lpRK/image134.png)

***Figure 20:
IMA module overview for ETSO-C153a CLASS IF***

**2. Requirements**

For ETSO-C153a CLASS IF, the IMA module provides shared resources for
the communication needs of hosted applications, modules and/or
components.

2.1. Functional requirements for ETSO-C153a CLASS IF:

IF.a) The IMA module shall provide to hosted applications, modules
and/or components, an Information Resource which has the capacity to
acquire from or to forward to an interface unit a set of data by
performing information coding and decoding operations.

IF.b) The IMA module shall provide to hosted applications, modules
and/or components, the capacity to use shared Information Resource
thanks to Data Threads handled through logical and/or physical
interface(s).

![](/static/files/file_jytjXw2lpRK/image135.png)

***Figure
21: The relationship between CLASS IF interface (IF) elements***

1.1. Characterisation requirements for ETSO-C153a CLASS IF:

IF.c) All performances of the shared Interface Unit of the IMA module
shall be characterised, including but not limited to the following:

1. performance of each Interface, including its throughput,
acquisition speed, forwarding speed, latency, jitter, coding rate and
decoding rate;

2. performance of (a) User Interface Mechanism(s), Protocol(s) and
Service(s) (e.g. socket timing, communication port timing,
technological time delay, etc.); and

3. performance of supported Data Thread Type (e.g. virtual link,
channel, pipe-and-filter, physical connection pin, etc.).

Note: These performance requirements are additional to those
applicable in Appendix 2.1 — COMMON.

IF.d) In addition to the Common Requirement 0,
the characterisation shall address the safety aspects of frozen data.

**2. Verification
procedures**

The following table gives the verification method for each MPS;
nevertheless, an alternative method may be proposed to the
certification authority:

<table bgcolor="#d9d9d9" cellpadding="7" cellspacing="0">
<col/>
<col/>
<col/>
<col/>
<col/>
<tr valign="top">
<td bgcolor="#808080">
Requirement
				identifier
</td>
<td bgcolor="#808080">
Verification
				method
</td>
<td bgcolor="#808080">
Test
				under normal conditions
</td>
<td bgcolor="#808080">
Test
				under 


environmental
				conditions
</td>
<td bgcolor="#808080">
Comment
</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
IF.a)
</td>
<td bgcolor="#d9d9d9">
T
</td>
<td bgcolor="#d9d9d9">
Y
</td>
<td bgcolor="#d9d9d9">
Y
</td>
<td bgcolor="#d9d9d9">
 

</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
IF.b)
</td>
<td bgcolor="#d9d9d9">
T
</td>
<td bgcolor="#d9d9d9">
Y
</td>
<td bgcolor="#d9d9d9">
Y
</td>
<td bgcolor="#d9d9d9">
 

</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
IF.c)
</td>
<td bgcolor="#d9d9d9">
T(A*)
</td>
<td bgcolor="#d9d9d9">
Y
</td>
<td bgcolor="#d9d9d9">
Y(1)
</td>
<td bgcolor="#d9d9d9">
 

</td>
</tr>
<tr valign="top">
<td bgcolor="#d9d9d9">
IF.d)
</td>
<td bgcolor="#d9d9d9">
T
				or A*
</td>
<td bgcolor="#d9d9d9">
 

</td>
<td bgcolor="#d9d9d9">
 

</td>
<td bgcolor="#d9d9d9">
 

</td>
</tr>
</table>

***Table 6:
Verification Acceptance Criteria***

(A\*) means that verification by the Analysis method is possible for
the item that cannot be tested.

Note (1): applicable for a functional subset 
cf. CO.gg).

[Amdt ETSO/10]

[Amdt ETSO/16]