Specifications

Allen-Bradley DF1 Driver Help
Upper WordLower Word
SEEEEEEE EMMMMMMM MMMMMMMM MMMMMMMM
Byte 3 Byte 2 Byte 1 Byte 0
Allen-Bradley PLC-5 devices transfer binary Floating-point data on the serial link in the following order:
Upper WordLower Word
Byte 2Byte 3Byte 0Byte 1
This means the upper word is received first, followed by the lower word. Due to this ordering, a swap of the
words is required, providing:
Lower WordUpper Word
Byte 0Byte 1Byte 2Byte 3
The result passed on to the client is as follows:
Byte 3Byte 2Byte 1Byte 0
Some PLC-5 emulated devices (such as the Avtron ADDvantage-32) already transfer binary Floating point data on
the serial link with the lower word first.
Lower WordUpper Word
Byte 0Byte 1Byte 2Byte 3
In this case, no swap is required. The result passed on to the client is as follows:
Byte 3Byte 2Byte 1Byte 0
Thus, the rule of thumb is if the device transfers the lower word first, then the upper word in the packet on the
serial link does not require word swapping. This only applies to PLC-5 emulated devices; that is, devices that use
the Allen-Bradley DF1 protocol with PLC-5 commands. Allen-Bradley PLC-5 devices always transfer the upper
word first followed by the lower word so the Float words must be swapped. This is the default setting.
Support Float Access to SLC/Micrologix N Files?
SLC and Micrologix users can select whether the driver will natively support Float access to Integer Files. The
default setting is Yes.
Cable Connections
This driver is an Allen-Bradley DF1 RS232 serial driver. It does not handle the token ring passing of a DH-485 or
DH+ network. When testing cable connections for this driver, first verify communications using the Allen Bradley
programming software.
l For Micrologix and SLC 500 series PLCs, if the APS driver selected is KF3/KE, Full-Duplex, Half-Duplex
Slave or Full Duplex (Micro) and communication is available with the PLC, this driver will also be able to
communicate using the same cabling and communication settings.
l For PLC5 series PLCs, if the PLC-5 programming software driver selected is Serial to PLC or KE/KF and
communication is available with the PLC, this driver will also be able to communicate using the same
cabling and communication settings.
Micrologix Series
Use the same cable as when using the Allen Bradley APS software.
SLC 500 Series - Direct connection
If the PLC has an RS232 port it can be connected directly using a standard RS232 null modem cable (which is the
same cable used in Allen Bradley APS software). The PLC port must be configured for Allen-Bradley DF1
communications, not DH-485 Master.
Note: This driver does not work in a direct connection to the DH-485 port of a SLC 500 series PLC using a 1747-
PIC converter the way the APS software does.
PLC5 Series - Direct connection
A direct connection can be made to the CH0 port of enhanced PLC5 processors using a standard RS232 null
modem cable. The port must be configured for Allen-Bradley DF1 communications.
DH-485 Networks
An Allen Bradley KF3 or compatible device is needed to connect the driver to the DH-485 network. A standard null
modem cable is used to connect the PC to the KF3 device.
DH+ Networks
There are three options for communicating to a device on DH+ using the Allen-Bradley DF1 Device Driver:
www. kepware.com
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