Specifications

Analog Output Modules
256
31007715 6/2008
Fallback Modes When communications are lost between the output module and the fieldbus master,
the module’s output channels must go to a known state where they will remain until
communications are restored. This is known as the channel’s fallback state. You
may configure fallback states for each channel individually. Fallback configuration is
accomplished in two steps:
z first by configuring fallback modes for each channel
z then (if necessary) configuring the fallback states
All output channels have a fallback mode—either predefined state or hold last value.
When a channel has predefined state as its fallback mode, it can be configured with
a fallback state, which can be any value in the valid range. When a channel has hold
last value as its fallback mode, it stays at its last known state when communication
is lost— it cannot be configured with a predefined fallback state.
By default, the fallback mode for both channels is a predefined state. If you want to
change the fallback mode to hold last value, you need to use the Advantys
configuration software:
Step Action Result
1 Double click on the STB AVO 1250 module
you want to configure in the island editor.
The selected STB AVO 1250
module opens in the software
module editor.
2 Expand the + Fallback Mode row by clicking
on the + sign.
Rows for Channel 1 and Channel
2 appear.
3 From the pull-down menu in the Value column
of the Channel 1 and/or Channel 1 row, select
the desired fallback mode setting.
Two choices appear in the pull-
down menus—Predefined and
Hod Last Value.
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