PEB2096 SIEMENS [Siemens Semiconductor Group], PEB2096 Datasheet - Page 35

• Manufacturer Part Number: PEB2096
• Description: Octal Transceiver for UPN Interfaces OCTAT-P
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

The monitor channel is used to convey message oriented information. This means that
an information in the monitor channel is transferred once, and the receiver stores that
message. There is a defined handshake procedure between the monitor channel
transmitter and the receiver in order to ensure a safe data transfer over the IOM-2
interface.
The OCTAT-P uses the monitor channel of IOM channel 0 for local programming and
reading (register access).
The monitor channel operates on an asynchronous basis. While data transfer on the bus
takes place synchronized to frame sync, the data flow is controlled by a handshake
procedure using the monitor channel receive bit (MR) and the monitor channel transmit
bit (MX). For example: data is placed onto the monitor channel and the MX bit is
activated (active low). This data will be transmitted repeatedly once per 8 kHz frame until
the transfer is acknowledged via the MR bit.
The monitor channel is in an idle condition when the MX bit is inactive in two or more
consecutive frames (indication of End Of Message EOM).
Before starting a transmission to the OCTAT-P, the microprocessor should verify that the
transmitter of the OCTAT-P is inactive, i.e. that a previous transmission has been
terminated.
The OCTAT-P has a monitor transmitter time-out function of minimum 4 ms
implemented. This prevents the monitor message to be transmitted continuously if the
monitor data won’t be acknowledged by the receiver.
An example for a P, ELIC and OCTAT-P communication is shown in figures 19 and 20.
First the Identification Register of the OCTAT-P may be read. Two bytes are transmitted
to the OCTAT-P and as a result of the read operation two bytes are returned to the
controller. In case of a write operation the data are only acknowledged and no data are
returned from the OCTAT-P to the controller.
The first byte of the data transmitted to the OCTAT-P always indicates the type of the
desired monitor operation (i.e. read or write to the internal registers).
The example shows the typical register access of the ELIC and gives a feeling about the
important bits.
The ELIC uses a 16-byte FIFO for transmission and reception of the monitor data.
Therefore the user doesn’t need to provide routines for the handshake protocol.
3.7
Semiconductor Group
IOM
®
-2 Interface Monitor Channel
35
PEB 2096
01.96