Design Guide
Revision 1.12
1998-08-12
HMS F
IELDBUS
S
YSTEMS
AB
Page 17 (35)
10 Application control (3FEh)
•
write only (application
⇐
AB-DT)
These registers are used to perform a proper handshake between the application and the AnyBus module.
A more detailed use can be found in the next chapter.
Function
Contents:
Description
Req. Control
02h
request to have control over DPRAM
Req. Release
01h
request to release control over DPRAM
Error indication
0Fh
error encountered – this message occurs only during the
initialisation, if the initialisation did not finish successfully
rest
Reserved for future use
Table 6. Application control
11 AB-DT control (3FFh)
•
read only (AB-DT
⇒
application)
These registers are used to perform a proper handshake between application and the AnyBus module. A
more detailed use can be found in the next chapter.
Function
Contents:
Description
Req. OK
1111 0010
OK for application to have control over DPRAM
Release OK
0000 0001
OK for application to release control over DPRAM
Error app.
1111 1111
error encountered, control stays at application
Error AB
0000 1111
error encountered, control stays at AnyBus module
rest
Reserved for future use.
Table 7. AB-DT control
By looking at the high nibble of the register, the application can easy check which side that owns access to
the DPRAM according the following:
Function
Contents:
Description
0000 xxxx
AnyBus module has control over DPRAM
1111 xxxx
application has control over DPRAM
Table 8. AB-DT control overview