Design Guide
Revision 1.12
1998-08-12
HMS F
IELDBUS
S
YSTEMS
AB
Page 16 (35)
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
Contents in bits:
Description
New data
0000 0000
0000 0001
No new data present
New data present
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
Contents in bits:
Description
Operation mode
xxxx xx00
xxxx xx01
initialisation phase
module initialised
Output mode
xxxx 00xx
xxxx 01xx
if fieldbus is stopped, all outputs are reset to 0 (default)
all outputs are FREEZED
Fieldbus status
xx00 xxxx
xx01 xxxx
fieldbus stopped
fieldbus is running
DPRAM owner
01xx xxxx
10xx xxxx
DataTransfer module owns the DPRAM
Application owns the DPRAM
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.
