HMS AnyBus DataTransfer Design Manual page 16

8 Fieldbus event (3FCh)
• read at any time (checking if new output data is available) (AB-DT ⇒ application)
• write/clear only while access to the DPRAM is permitted (AB-DT ⇐application)
These registers indicate, if there is new output data available for the application – the flag is set to 1. If the
application is using this bit in there program, it should be cleared at any time an output update was
performed.
If this flag is not used, no action is necessary since the AnyBus module will only set this flag, but never
check the contents.
Function
New data
9 System status (3FDh)
• read / write during initialisation (application ⇐⇒ AB-DT)
• read only (AB-DT⇒ application)
• read at any time (owning DPRAM is not necessary)
The status information of the AB-DT module and of the underlying fieldbus are shown in this register.
There are only two bits that can be reconfigured during initialisation and they are the bits that indicates
output-mode.
Function
Operation mode
Output mode
Fieldbus status
DPRAM owner
Table 5. System status
This register is read only! It will provide information about the status of the fieldbus. During initialisation it
will contain 00h. After the initialisation is completed, valid data is available.
If the application tries to access the DPRAM more than one second the control will be forced back to the
AnyBus module. The AnyBus module is indicating this by changing DPRAM-owner from 10 to 01. The
AnyBus module waits one millisecond before it starts to accesses the DPRAM again.
Contents in bits: Description
0000 0000 No new data present
0000 0001 New data present
Contents in bits: Description
xxxx xx00 initialisation phase
xxxx xx01 module initialised
xxxx 00xx if fieldbus is stopped, all outputs are reset to 0 (default)
xxxx 01xx all outputs are FREEZED
xx00 xxxx fieldbus stopped
xx01 xxxx fieldbus is running
01xx xxxx DataTransfer module owns the DPRAM
10xx xxxx Application owns the DPRAM
HMS F S AB
IELDBUS YSTEMS
Design Guide
Revision 1.12
1998-08-12
Page 16 (35)