MATRIX Data Type

A variable of the MATRIX data type encapsulates a two dimensional matrix of 32-bit floating-point values (corresponding to the IEC 61131-3 data type REAL) in [row][column] format.

Literal values

Literal values of MATRIX variables are expressed as follows, using the syntactic conventions defined in Annex A of IEC 61131-3:

matrix_literal ::= '[' [vector_literal {',' vector_literal}] ']' vector_literal ::= '[' [float_value {',' float_value}] ']'

The syntax of float_value is any string accepted by the java.lang.Float.valueOf(String) method.

Each vector_literal element represents a row of the matrix; for instance, the literal [[1,2],[3,4]] represents the matrix

1.0 2.0 3.0 4.0

Missing elements are assigned zero values; for instance, the literal [[],[1,2],[3,4,5]] represents the matrix

0.0 0.0 0.0 1.0 2.0 0.0 3.0 4.0 5.0

For examples of the use of MATRIX literals, see the TEST_MATRIX system configuration and the TEST_MATRIX application of the CODEC_TEST2 system configuration, as well as the IN_MATRIX and OUT_MATRIX FB types.

ASN.1 Encoding

MATRIX data is transferred according to the following modified ASN.1 syntax:

ARRAY ::= [APPLICATION 23] IMPLICIT SEQUENCE { rows IMPLICIT USINT, cols IMPLICIT USINT, IMPLICIT SEQUENCE OF IMPLICIT REAL}

The encoding of MATRIX elements is constructed in the sense of ISO/IEC 8825, with the following extensions to the COMPACT encoding described in Annex E of IEC 61499-1:

rows and cols, representing the number of rows and columns in the matrix respectively, are encoded as values of the USINT type without identifier or length octets, i.e., as two successive 8-bit unsigned integers.
- This restricts the maximum number of elements of a MATRIX to 65025 (255×255). However, the actual length may be further restricted by the maximum number of octets that can be transferred by the underlying transport protocol. For UDP, this number is 65508. Then, for instance, the maximum transmittable length of a MATRIX using UDP would be (maximum octets - tag octets - length octets)/(element length) = (65508-1-2)/32 = 2047 elements. For instance, a matrix with 45 rows and 45 columns, containing 2025 elements, would fit in a UDP packet.
The matrix contents are encoded using the COMPACT syntax for an ARRAY of IEC 61131-3 REAL values, without any tag or length subfields.
Data is encoded in column order; for instance, the matrix
0.0 0.0 0.0 1.0 2.0 0.0 3.0 4.0 5.0
would be encoded in the order (0.0,1.0,3.0,0.0,2.0,4.0,0.0,0.0,5.0).

For an example of the application of these encoding rules, see the TEST_MATRIX application of the CODEC_TEST2 system configuration.