19
11.1.3 Positioning algorithm
a positioning algorithm (position closed loop
control) is implemented on the EPI
2
DPV1
interface card.
Positioning function compares the position,
received from the base card, with the position
request received from the bus. If the difference
between ‘position request and present position’
is greater than the ‘dead band’ an open or a
close command is sent to the base card. Dead
band is configurable via bus from 0,3 to 2,0%.
11.1.4 Diagnostic message
the EPI
2
DPV1 interface manages the
diagnostic indication coming from the actuator
as stated by the Profibus DP V1 standard.
When the EPI
2
DPV1 interface needs to notify
a fault to the master while in data exchange
mode, it changes the function code in its
response message to ‘high priority’. During
the next regular bus cycle the master in turn
master epi2_dpV1
Data exchange request
Data exchange response
Data exchange request
Data exchange responde
(Function code = high priority)
Slave_Diag request
Salve-Diag response (Diag Ext-Diag = 1)
Data exchange request
Data exchange response
Data exchange request
Data exchange response
(Function code = high priority)
Slave_Diag request
Slave_Diag response (Diag.Ext_Diag = 0)
Data exchange request
Data exchange response
Fault on
Fault off
ms lsb
Octet 1
standard diagnostic block
6 octets
Octet 2
Octet 3
Octet 4
Octet 5
Octet 6
type IrD, length
identifier related diagnostic block
2 Octets
0 0 0 0 a a a a
type DrD, Lenght
device related diagnostic block
status messages
6 octets
Identifier, status_type
slot_number
status_specifier
d d d d d d d d
d d d d d d d d
the diagnostic message implemented by EPI2_DPV1 has the following structure:
Keystone
OM9 - EPI2 PrOfIbus DPV1 IntErfacE
InstallatIon & MaIntenance InstructIons
send a ‘slave_Diag’ request that is answered
with a ‘slave_Diag’ response. the availability
of specific diagnosis information is notified by
Dia.Ext_Diag flag set to 1. Once the master
was able to catch the diagnosis information it
returns to the standard cyclic data exchange
mode. to notify the termination of the diagnosis
incident the EPI2_DPV1 interface send a ‘high
priority’ response. the master answers with
a ‘slave_Diag’ request that is followed by a
‘slave_Diag’ response with Dia.Ext_Diag flag
set to 0.
