Rockwell Automation 20-750-PBUS Profibus DPV1 Option Module - Manual (Page 20)

20 Rockwell Automation Publication 750COM-UM004B-EN-P - September 2012
Chapter 2 Installing the Option Module
Setting the Endianness and
Node Address Switches Set the Endianness of the option module with Byte Swap switch 8 (see Figure 1 ).
The Byte Swap switch can be set to either open ‘0’ (Little Endian) or closed ‘1’
(Big Endian) data formats for the cyclic data exchanged on the network.
The
cyclic data consists of the following items:
• CTRL: Logic Command Word (4 bytes)
• REF: Speed Reference (4 bytes)
• STAT: Logic Status Word (4 bytes)
• FEEDBACK: Speed Feedback (4 bytes)
• 0 to 16 Datalinks (4 bytes each)
Depending on the setting of the Byte Swap switch 8, the 4 bytes for each of the
above data items are swapped.
Figure 1 - Setting Option Module Node Address Switches
Set the Node Address by setting Node Address switches 1 through 7 to their
binary equivalent, where '0' and '1' indicate switch positions 'Open' and 'Closed'
respectively.
Table 1 lists node addresses and the corresponding Node Address
switch settings required to set that respective address.
IMPORTANT Each node on the Profibus network must have a unique address. Set the
node address before power is applied because the option module
detects the node address during initialization (Power On Reset). To
change a node address, you must set the new value and then remove
and reapply power to (or reset) the option module.
7
8
6
5
4
3
2
1
1
4
3
2
5
6
7
8
Node Addr
Switches
1…7
Byte Swap
Switch 8