4

4421B–ASSP–10/05

TSSIO16E

4.

Functional Features

4.1

Content of Identifier Field

The TSSIO16E circuit identifier field is structured as shown below.

The local address consists of bits I1, I2 and I3 of the identifier field for the VAN frame addressing

the circuit, the Bit I1 indicates reading or writing. The table below gives the significance of these

bits.

4.2

Addressing of ports A and B and of COMMAND and STATUS registers

The specific functions of the circuit are activated by the selection of one or two ports depending

on the local address decoding (see § 4.1) as contained in the identifier field of the VAN frame

received by the circuit and by the content of the data bytes for this frame.

4.2.1

Local address 0 and 1

Writing and reading of these registers are described in paragraph 4.4.

The writing of the COMMAND register uses a single data byte. The reading of the STATUS reg-

ister sends a data byte to RANK 16.

External wired address

Identifier field

(undecoded)

Local address

I3

I2

I1

local address

action

0

0

0

0

writing of VAN CONTROL register

0

0

1

1

reading of VAN STATUS register (RANK 16)

0

1

0

2

writing of port A

0

1

1

3

reading of port A (RANK 16)

1

0

0

4

writing of port AB

1

0

1

5

reading of port AB (RANK 16)

1

1

0

6

writing of port B

1

1

1

7

reading of port B (RANK 16)

I3

I2

I1

Writing of the COMMAND register

0

0

0

Reading of the STATUS register

0

0

1