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devicenet command

Started by pmm April 10, 2004
Hello ,
i am developing an application on the Digital IO control, and i am
implementing a DiscreteInputPoint and DiscreteOutputPoint objects in
the devicenet stack .i have a confusion, that is what will be the
commands sent by a master to a specific DiscreteInputPoint .
To put it neatly have a DiscreteinputPoint object which shall
implements GetAttibuteSingle function .if the master wants to know the
status he will ofcourse send a command, what will be the structure of
the command,ie what master will send in the parameter of
getattributesingle function
sorry for my bad english
kindly reply 
Regards
PMM
"pmm" <muralipmanohar@hotmail.com> wrote in message
news:1f1fe31f.0404092039.5ebbc6e7@posting.google.com...
> Hello , > i am developing an application on the Digital IO control, and i am > implementing a DiscreteInputPoint and DiscreteOutputPoint objects in > the devicenet stack .i have a confusion, that is what will be the > commands sent by a master to a specific DiscreteInputPoint . > To put it neatly have a DiscreteinputPoint object which shall > implements GetAttibuteSingle function .if the master wants to know the > status he will ofcourse send a command, what will be the structure of > the command,ie what master will send in the parameter of > getattributesingle function > sorry for my bad english > kindly reply > Regards > PMM
Typically, a master device gets data from a slave using one of the Predefined Master/Slave Connection set messages which are "I/O" messages. But that would not involve using the GetAttributeSingle service. In order to use the GetAttributeSingle service, the client (not necessarily a master) would use "explicit" messaging. The explicit message protocol is defined in section 4-2 of Volume 1 of the DeviceNet Specification. The message body of an explicit message request message typically contains the service code followed by the class code, the instance number, and finally the service specific data. The service specific data of the GetAttributeSingle service is the attribute ID of attribute you wish to get. Assuming, for example, that the explicit message connection was created to use 1 byte class codes and 1 byte instance numbers, then the message body of the request to GetAttributeSingle the Value attribute of instance 1 of the Discrete Input Point Object would look like this: Service Code (GetAttrSingle), Class Code (DIP), Instance (1), Attribute ID (Value). Or specifically: 0x0E, 0x08, 0x01, 0x03 -- Kevin
"Kevin Kramb" <kekramb.invalid@ra.rockwell.com.invalid> wrote in message news:<107iu6tim7pv986@corp.supernews.com>...
> "pmm" <muralipmanohar@hotmail.com> wrote in message > news:1f1fe31f.0404092039.5ebbc6e7@posting.google.com... > > Hello , > > i am developing an application on the Digital IO control, and i am > > implementing a DiscreteInputPoint and DiscreteOutputPoint objects in > > the devicenet stack .i have a confusion, that is what will be the > > commands sent by a master to a specific DiscreteInputPoint . > > To put it neatly have a DiscreteinputPoint object which shall > > implements GetAttibuteSingle function .if the master wants to know the > > status he will ofcourse send a command, what will be the structure of > > the command,ie what master will send in the parameter of > > getattributesingle function > > sorry for my bad english > > kindly reply > > Regards > > PMM > > Typically, a master device gets data from a slave using one of > the Predefined Master/Slave Connection set messages which are "I/O" > messages. But that would not involve using the GetAttributeSingle > service. > > In order to use the GetAttributeSingle service, the client (not > necessarily a master) would use "explicit" messaging. The explicit > message protocol is defined in section 4-2 of Volume 1 of the > DeviceNet Specification. The message body of an explicit message > request message typically contains the service code followed by the > class code, the instance number, and finally the service specific > data. The service specific data of the GetAttributeSingle service > is the attribute ID of attribute you wish to get. > > Assuming, for example, that the explicit message connection was > created to use 1 byte class codes and 1 byte instance numbers, then > the message body of the request to GetAttributeSingle the Value > attribute of instance 1 of the Discrete Input Point Object would > look like this: > > Service Code (GetAttrSingle), Class Code (DIP), Instance (1), > Attribute ID (Value). Or specifically: > 0x0E, 0x08, 0x01, 0x03 > > -- Kevin
Thanx I think i need to read the spec again regards PMM

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