About Grouping Adjacent Modules Into One Logical Module; Guidelines For Grouping Modules - Honeywell Experion PKS User Manual

6.6 About grouping adjacent modules into one logical module

Attention
This feature is available in Experion R410.2 and later.
Though a single PDC can support up to 32 channels (GENDSB) or 16 channels (GENIODSB), sometimes not
all channels of a module are used. In such scenarios, you can pack IO channels from several IO modules into
one PDC to minimize number of PDCs. This reduces the load on PDA and controller by decreasing the number
of PDC-PIOMB connections.
Grouping of adjacent modules into one logical module is supported for the GENDSB and the GENIODSB. This
module grouping enables you to select multiple adjacent IO modules and create one logical module. This logical
module can have one net tag name and this net tag name can be associated with a single PDC.
Example: Consider a scenario where you have three IO modules but you are using only three channels of each
module. In this case, you need three PDCs for three modules, three PIOMBs, and three connections. However,
with module grouping you can group all the modules into one group and configure one net tag name and
associate this net tag name with a single PDC. This ensures that the data is available in a single PDC and this
PDC can be associated with a single PIOMB.
To enable module grouping, the Address Table page and the Process Data page in the field network
configuration tool (Profibus Network Configuration Tool) is replaced by the Address Management page. For
more information, refer to the section "Grouping adjacent modules into one logical module" on page 82.

6.6.1 Guidelines for grouping modules

The following list summarizes the guidelines for grouping the modules together.
• You can group only the adjacent modules with consecutive addresses and there must not be any empty slot
in between the grouped modules.
• You can configure the input modules as one group and the output modules as another. However, you cannot
configure both input and output modules as one group.
• You can group bidirectional modules as groups. However, you cannot group unidirectional and bidirectional
modules as one group.
• When grouping bidirectional modules, you must ensure that all the modules in the group are consistent with
respect to positioning of the input and output channels. However, you cannot randomly configure the first
channel as input and second channel as output and then again third channel as input and fourth channel as
output and so on.
• You must start channel numbering either from 0 or 1, but should be consistent within the group. For example
if you start numbering the channels from 1, then channel numbers must start from 1 for all the modules in
that group. Similarly, if you start numbering the channels from 0, then channel numbers must start from 0 for
all the modules in that group.
• For all the grouped PDCs (PDC which is configured for a grouped module), you must correctly enter the
CHNNUMBER parameter. The channel numbers must be entered in the same order as they are grouped.
– Example 1: Assume four input modules each having four channels are grouped together, then the
NUMCHANNEL must be entered as 16 (4+4+4+4) and the CHNNUMBER parameter should contain: 0,
1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3 or 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4 (if the channel numbering
is started from 1).
– Example 2: Assume three output modules on slots 5, 6, 7 are grouped together. The module on slot 5 has
three channels, the module on slot 6 has four channels and the module on slot 7 has eight channels. Then
the NUMCHANNEL should be entered as 15 (3+4+8) and the CHNNUMBER parameter should be
entered as displayed in the following figure.
6 PROTOCOL BLOCK
79