DESCRIPTION AND OPERATION
DATA TRANSFER
I-E96-211A
2 - 3
Serial Channels
There are two independent, general purpose serial channels on
the MFC. One is used for language support (C and BASIC).
Each channel is capable of supporting standard baud rates up
to 19.2 kilobaud. Standard D-type connectors are available on
the NTMF01 termination unit or NIMF01 termination module.
Note that one channel also can be used as RS-485.
Module Bus
The module bus provides a 83.3 kilobaud peer-to-peer commu-
nication link capable of supporting up to 32 drops.
Redundancy Link
The redundancy link is a 25 kilobit serial link between a pri-
mary and backup MFC in redundant configurations. As the
primary module executes, the backup module waits in hot
standby mode and receives a copy of all block outputs over this
link. If for any reason, the primary module fails, the backup
module takes over immediately without any process
interruption.
Station Link
Station link controls the serial communication between the
MFC and the panel stations. It provides a 5 kilobaud serial
channel for up to eight stations (IISAC01 or NDCS03). This link
connects to the termination unit or termination module for
control stations via the NTMF01 or NIMF01 and the cable
NKSE01.
DATA TRANSFER
The IMMFC03 uses two busses for communication purposes:
The module bus and the slave expander bus. Through the
module bus, the MFC communicates with other control mod-
ules in its process control unit (PCU). The module bus is a
serial bus located on the MMU backplane. The slave expander
bus is an 8 bit parallel bus located on the MMU backplane. It
provides the path for bidirectional communications with slave
modules. This bus, through a 12 position dipshunt, can be
broken to create separate busses for different masters.
Data transfer between the MFC and its slaves occurs on the
slave expander bus. The MFC is able to execute four types of
data transfer functions. They are:
•
Write a command to a slave.
•
Request a slave status.
•
Write data to a slave.
•
Read data from a slave.
