5
Functions
Figure 2. Functions of the SRIO 500M unit.
Event logging
Using the SACO 100M protocol the SRIO
500M unit polls the SPA bus units and the
slave devices connected to the SRIO 500M unit
for event data including time markings. The
events are sorted in time order and stored in the
event buffer.
From the event buffer the events are delivered
to the host computer.
Data acquisition
The user can define up to 500 data items for
the data base. A data item can be one of the
following data types:
- DI: digital input data (digital status data)
- AI: analog input data (measured data)
- DO:digital output data (digital control data)
- AO: analog output data (analog control data)
- EV: event data (analog status data)
Cyclic data acquisition (polling):
The SRIO 500M unit acquires DI and AI data
for the data base by cyclic polling.
Event based data acquisition:
The EV data is acquired by converting slave
event codes, acquired by the event acquisition,
to analog data values.
Real-time clock
The SRIO 500M unit includes a real-time clock.
The clock contains the current time including
time from years to milliseconds. A battery back-
up clock chip is used to maintain time during
power off situations.
The clock can be set by the user through the
programming terminal or host interface. The
clock can also be synchronized with an external
minute pulse.
Slave interf.
SPA bus
protocol
SPA bus slaves
Data
acquisition
Event
acquisition
Real-time
clock
Changed
queue
Event
buffer
Config.
data
Host interface
ANSI X3.28
protocol
Host interface
SACO 100M
protocol
Host computer
User interface
(Commands)
Display
terminal
or printer
Data
base
SPA bus
