Filter
Top Products
GFK-0825F Chapter 2 Description 2-3
2
Bus Interface Unit Power Supply
The power supply in the Bus Interface Unit provides power for the Bus Interface Unit itself and
logic power for all I/O modules that may potentially be installed at that station. External power
must be supplied for field wiring of input and output devices.
The power supply is not damaged by either of the following:
Reversing input voltage on terminals 1 and 2.
Temporary
overcurrent conditions on the 6.5 VDC output.
Timing
The Bus Interface Unit provides power to all I/O modules that are installed at the station. I/O
module operation is governed by a System Reset signal to ensure controlled operation during the
power up and shut down processes. As shown in the timing diagram below, momentary power
losses of less than 10 mS (for 24VDC BIU) or 20mS (for 115VAC/125VDC BIU) do not affect I/O
module operation. Longer power losses generate a Reset for all system I/O modules.
Input Power
On
Momentary
Power
Loss
Voltage
Overshoot
5% (max)
95% (min)
Hold
Up
Time
200mS
(min)
10mS
(min)
3mS
(min)
3mS
(min)
200mS
(min)
RST*
6.5V Output
24VDC
Nominal
or 115 VAC
Nominal
Voltage
Overshoot
5% (max)
Input Power
Off
Hold
Up
Time
Minimum:
10mS for 24VDC BIU
20mS for 115VAC/125VDC BIU