Technical data

66 • Feldbus Coupler 750-344 / -345
Diagnostics
WAGO-I/O-SYSTEM 750
INTERBUS
3.1.6 Diagnostics
3.1.6.1 Standard Couplers 750-344 and 750-345
The bus coupler reports an error in the periphery to the master when there is a
disturbance of data bus operation.
The bus coupler cancels the error message when the error has been eliminated.
3.1.6.2 Diagnostics Couplers 750-344/000-003 and 750-345/000-003
In addition to providing periphery error messages (see above), this bus coupler
also provides diagnostics information to the process data.
3.1.6.2.1 Buffer for Diagnostics Data (only
with Diagnostics Couplers)
The diagnostics information is buffered in the bus coupler until it is requested
by the master. When error data is output, the oldest error is output first. The
buffer can accommodate a total of 64 entries. Other diagnostics information is
discarded when this buffer becomes completely full. New entries are not
accepted until the higher-order PLC has read and acknowledged an existing
entry, thus creating space in the buffer for other (new) entries.
Data transmission between the master and the bus coupler is synchronized
using a hand-shake technique. The diagnostics information is transferred to the
process input data from the bus coupler. Confirmation of the data, or deleting
of diagnostics information takes place in the process output data.
Diagnostics information is obtained by the bus coupler through cyclic
querying of the internal diagnostics buffer. Diagnostics information for a
module is processed on each query of the associated function.