User`s guide

32 DC 900-1339H
FMP Programmer’s Guide
gram and the Freeway server or embedded ICP is always in ASCII and is translated by
the FMP software as required.
2.1.6 Message Transmission
In addition to receiving the market feeds, the FMP product can transmit data in the
same format. This capability is not usually used during normal operations; however, it
can be used for port-to-port loopback testing.
The client sends data to the FMP software as a complete message. A message consists of
one buffer of text data. The FMP control characters are not included in the message.
The control characters are inserted by FMP before transmitting the data except when
the message blocking option (Section 4.13 on page 81) is set to no blocking. Once in
memory, FMP may transmit the messages in smaller blocks, called transmission blocks,
to provide more accurate and efficient error control. The FMP software begins each
transmission block with a start-of-header (SOH) control character and ends each mes-
sage with an end-of-text (ETX) character. All data blocking and deblocking is transpar-
ent to the user; however, the ICP message buffer size (Section 3.4.1.3 on page 48) and
transmission block size (Section 4.7 on page 72) must be defined by the user before a
communication link is placed in operation (if other than the default values are
required).
2.2 FMP Access Modes
Each FMP session on a link can be set to one of the following access modes: Manager,
Shared Manager, User, or Control. The access mode is defined in the DLI configuration
file (Chapter 5) using the client-related “
mode” parameter (described in the Freeway
Data Link Interface Reference Guide).
When several sessions have access to a link, each non-Control session receives a copy of
any message listed in Table 2–1. A maximum of six non-Control sessions may register
on any one link. Only one Control session is allowed per link.