BECKHOFF BK5200 - Manual (Page 18)

Basic Principles
18 BK52x0
the interaction of peripheral devices and their controllers is, in a basic
sense, only assured for a single byte. In other words, the bits of a byte are
written or read together. Byte consistency is sufficient for handling digital
signals. Whenever values have a length of more than 8 bits, analog values
for instance, the consistency must be extended. The different bus systems
guarantee consistency up to the required length. Correct transfer of the
consistent data from the bus system master to the controller is important.
The corresponding manual for the bus system will provide a detailed
description of the correct procedure, in particular the description of the
master interfaces used. Those chapters of this manual that deal with the
fieldbus refer to the most widespread interfaces.
Complex signal processing All the byte-oriented signal channels such as RS232, RS485 or
incremental encoders operate to some extent with byte lengths of more
than two. Apart from the difference in length, they are always handled
similarly to the analog signals.
Start-up procedure and Diagnostics
After switching on, the Bus Coupler immediately checks the connected
configuration. Error-free start-up is signalled by the red "I/O ERR“ LED
being extinguished. If the “I/O ERR” LED blinks, an error in the area of the
terminals is indicated. The error code can be determined from the
frequency and number of blinks. This permits rapid rectification of the error.
There is a detailed description in the section on "The diagnostic LEDs".
The diagnostic LEDs The Bus Coupler has two groups of LEDs for the display of status. The
upper group with four LEDs indicates the status of the respective fieldbus.
The significance of the “fieldbus status“ LED is explained in the relevant
sections of this manual - it conforms to conventional fieldbus displays.
On the upper right hand side of the Bus Couplers are two more green
LEDs that indicate the supply voltage. The left hand LED indicates the
presence of the 24 V supply for the Bus Coupler. The right hand LED
indicates the presence of the supply to the power contacts.
Local errors Two LEDs, the “I/O LEDs”, in the area below the field bus status LEDs
referred to above, serve to indicate the operating status of the Bus
Terminals and the connections to these terminals. The green LED lights up
in order to indicate fault-free operation. The red LED blinks with two
different frequencies in order to indicate an error. The error is encoded in
the blinks as follows:
Fast blinking Start of the error code
First slow sequence Error code
Blink code
Second slow sequence Error code argument