GFK-0825F Chapter 8 Datagrams 8-7
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BIU
Configuration Data
For a Bus Interface Unit, the data format of configuration data transferred by Read Configuration
Reply and Write Configuration datagrams is slightly different than the format for other Genius
devices. Instead of an offs et, the data specifies th e slot number of a specific device in the Field
Control Station. The length specified must exactly match the length of the configuration data for
the module (Bus Interface Unit or other module in the station); partial configuration data cannot be
written. For programming instructions, you will need to refer to the Bus Controller User's Manual
for the PLC. For the Series 90-70 PLC, COMREQ 15 must be used with a Read Configuration
datagram.
Configuration files for conventional Field Control modules can be read or written one module per
message. However, the configuration files of intelligent modules may exceed the 128-byte
maximum length of a Genius message. Therefore, any Write Configuration to an intelligent module
must be contained within a Begi n/End Packet Sequence.
Read Configuration Data
Subfunction Code: 02 hex
The Read Configuration Datagram is used to read configuration data. The datagram format is
different for conventional Field Control modules or intelligent modules.

Read Configuration Data Format for Field Control Conventional Modules

Byte # Description
0Slot number
1 Length (will return minimum 6 bytes to maximum 128 bytes, or specific
amount requ es ted. It can b e m o re or less tha n t he configur ed size for
the slot. If more data is requested than is available for a slot, the extra
data bytes will contain zeros.)

Read Configuration Datagram Format for Field Control Intelligent Modules

Configuration data for the BIU and other intelligent modules is transmitted in packets. Depending
on the module type, there can be many packets. Each packet can be up to 128 bytes long.
Byte # Description
0Slot number in bottom nibble, Intelligent Packet in upper nibble.
Examples:
01(hex) reads packet 0 of intelligent module in slot 1
11(hex) reads packet 1 of int el li g ent m od ul e in sl ot 1.
1 Length in bytes (maximum per packet is 128)
2 (optional) . If the slot num b er is 0 (the loc ation of the BI U), and this byt e
is not inclu d ed or if it is set t o FF(hex), the BI U configurat i on is
returned.
If this byte is set to 01(hex) through 10(hex), the appropriate group
information is returned.