PEF2054 SIEMENS [Siemens Semiconductor Group], PEF2054 Datasheet - Page 200

• Manufacturer Part Number: PEF2054
• Description: ICs for Communications
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

then be transmitted byte by byte to the subscriber circuit.
If the handshake facility is disabled (IOM-1/SLD), the data is sent at a speed of one byte
per frame.
If the handshake facility is enabled (IOM-2), each data byte must be acknowledged by
the subscriber circuit before the next one is sent. The transfer speed depends therefore
on the reaction time of the subscriber circuit. The EPIC can transmit a message at a
maximum speed of one byte per two frames.
In order to avoid blocking the software when a subscriber circuit fails to acknowledge a
message, a software time out, which resets the monitor transfer (CMDR = 01
be implemented.
If the remote partner aborts the reception of an arriving message i.e. if the EPIC detects
an inactive MR bit during at least two consecutive frames, the transmit operation will be
stopped, the ISTA:MFFI interrupt will be generated and the STAR:MFAB bit will be set
to 1. The CMDR:MFFR bit should then be set to clear the MFAB bit before the next
transfer.
When all data bytes of the MFFIFO have been sent (and eventually acknowledged) the
EPIC generates an ISTA:MFFI interrupt indicating the end of the transfer. The MF
handler may then be pointed to another subscriber address for another monitor transfer.
5.5.3.2 Description of the MF Channel Commands
Transmit Command
The transmit command can be used for sending MF data to a single subscriber circuit
when no answer is expected. It is applicable for both handshake and non handshake
protocols. The message (up to 16 bytes) can be written to the MFFIFO after interrogation
of the STAR register. After writing of the MF channel address to MFSAR the transfer can
be started using the transmit command (CMDR = 04
Semiconductor Group
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H
). The contents of the MFFIFO will
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) should