BECKHOFF BC7300 - Manual (Page 46)

Questions and Answers
46 BC7300
Questions and Answers
General
No communication with the BC7300
Problem You cannot log in with either KS2000 nor TwinCAT (BC).
Solution
Set the address selection switch to "00" and start the Bus Terminal
Controller again.
Mapping of the digital and the byte-oriented Bus Terminals
onto a fixed address
Problem You want a constant start address for the digital inputs and outputs.
Solution
With the KS2000 software, you can enter an offset start value for the digital
inputs and outputs in table 0. The byte-oriented Bus Terminals should not
jut into this process image, i.e. no overlap should occur.
Table 0:
Register 19 offset for digital outputs
Register 20 offset for digital inputs
"0" is the default setting (automatic Bus Terminal mapping)
Example You have a KL3002 and a KL2012. In the default case, the KL3002 maps
onto %IB0- %IB7 and %QB0-QB7 in the memory. The digital output
terminal would now map to %QX8.0 and %QX8.1. As soon as you now plug
another byte-oriented Bus Terminal, the process image of the digital Bus
Terminal is moved to a higher memory. You can now pre-empt this by
entering 20 in register 19. This means that KL2012 now maps onto
%QX20.0 and %QX20.1.
Drop of the digital outputs
Problem Your digital outputs drop away.
Solution
Your program takes longer than 100 ms. Because the internal K-Bus runs
synchronous with your PLC program, it is no longer triggered early enough,
and the Bus Terminal watchdog becomes active. This can be rectified by
triggering a short refresh of the K-Bus. The setting can be carried out with
the KS2000 software.
Table 1 register 17
LowByte cycle time to K-Bus refresh (<= 80 ms)
HighByte Retries
Recommendation Enter 0x0350 in table 1, register 17, i.e. three retries, all at 80 ms.
Note that this causes the Bus Terminal watchdog to increase to 240 ms
during a fault condition (this is not true in case of a K-Bus error, where the
watchdog will remain at 100 ms).