You must define the channel data type if you have used the configurable input/output PDCs.
In the Channel Data offset column, select the channel data offset of the digital input/output channel.
In the Bit offset column, select the bit offset of the digital input/output channel.
If you have used the fixed PDC types, the bit offsets are displayed automatically.
You must define the bit offsets if you have used the configurable input/output PDCs.
In the Low Range column, type the lowest raw value that the channel supports. This parameter is applicable
only for the analog input/output PDCs. For digital input/output PDCs, this parameter is non-editable.
The channel low range must be less than the channel high range. If channel low range is greater than or equal to
channel high range, the error message "RangeorLimitCrossover" appears during the load of the DSB block. In
addition, the PDC will go into the "Config Load Fail" state, and the DSB will go into the "Configuration Error"
In the High Range column, type the highest raw value that the channel supports. This parameter is
applicable only for the analog input/output PDCs. For digital input/output PDCs, this parameter is non-
To prevent the process data values from being scaled, you can set the channel high and low range as "NaN." When
this is performed, the process value is limited by the values supported by the data type. If PVLO and PVHI ranges
are set to NaN then RAW float of the ranges can be read for the PDC.
In the Init Value column, define values for each output channel from which the channels must initialize after
recovering from a network down condition. You can define the following values as initial values.
0 - 100
For AO channels, numeric initialization value defines percentage value of the output.
For DO channels, initialization value 0 defines OFF state of the channel and value 1 defines ON state of
NaN - If the initialization value is defined as NaN, the output channels (AO and DO) hold the last output
0 - If the initialization value is defined as 0, the AO channel initializes to 0 and the DO channel is cleared
to 0 during all error scenarios. However, for the AO channel, if you enter a small non-zero value like
0.001, the channel value initializes to the low range defined for the channel.
For more information, refer to the section "About initialization of AO/DO channels from user-defined
values" on page 152.
7.16.1 Generic DSB specific PDC configuration guidelines
The following list summarizes the Generic DSB specific PDC configuration guidelines that you must remember
while configuring the Generic DSB PDC.
The number of PDCs supported by GENDSB is 16 and GENIODSB is 64.
In the Number of Channels column, you must enter the number of channels manually.
In the Channel Number column, you must enter the channel numbers in increasing order. If not, this may
result in an unknown channel status behavior.
You can view the PDC State, Data Module Number, Data Size, Channel Status, Ch data Boolean, Numeric raw
data, Floating point value values in the Monitoring view after the DSB is loaded.
You can set the analog channel output value (Numeric raw data/Floating point value) or the digital channel
output value (Ch data Boolean) from the Monitoring view if you have not associated a PDC to a PIOMB.
7 DEVICE SUPPORT BLOCK (DSB)