TANGO Device Server

Introduction:

Control of SR power supplies.. The Device Server is meant to provide control of PSI Power Supply Controllers. The DS is basic/universal, it means that it can be used as a base for developing Device Servers for PSI PSC intended for specific usage which requires implementing additional functions (ex. upload/download waveform).

The Device Server can use two types of hardware connection to communicate with PSI PSC: serial (RS232) or fiber. The connection type is determined by setting the property: ConnectionType (0 for fiber and 1 for serial).

For simplicity, PSC DS connected by serial connection will be called serial DS, PSC DS connected by fiber connection will be called fiber DS.

Serial connection is considered as local and 'service', it is not supposed to be used on normal basis, just in extraordinary cases.
Fiber connection is considered a default connection meant to be used most of the time.

Fiber connection uses PCI/cPCI Carrier Card. Each card carries two Industrial Pack (IP), each having two channels. Each channel of IP is connected to one PSC. One IP is represented in /dev/ folder as node called pscipX (X is number).
If fiber connection is to be used, the property 'FODevice' needs to be set (ex '/dev/pscip0') along with 'Channel' property (0 or 1).

Serial connection uses PySerial Device Server. The property 'TangoDevice' needs to be set inicating the Py Serial name and localization (ex. 'ws/pc-test/ocem00-serial ').

For the PySerial to work properly, the following attributes need to be set:



Attr name	value
Bautrate	115200
DataBits	8
Parity	odd
Port	Correct port to which PSC is connected (ex. /dev/ttyR0)
StopBits	1



In theory, instead of PySerial DS, any DS can be used instead of PySerial without any changes to PSI SD as long as the following commands are implemented:
• 'ReadLine' for reading data,
• 'Write' for writing
• 'Open'
• 'Close'
• 'State'
Both connections can be used simultaneously only for reading. When writing, a priority is given to one of the Device Servers The priority can be only set Serial DS. It means that DS connected by fiber cannot regain writing priority , it has to be granted priority. For safety reasons the priority is granted to serial DS as long as it is connected to PSC. To be precise, the priority for serial DS is granted as soon as it attempts the first write. The priority is set to fiber DS only if serial DS is disconnected from PSC.

CAUTION: If the priority is set to serial DS and an attempt to write is made by fiber DS, the fiber DS gives no error message, it looks as if the operation was successful, however, the value is not written.

The following documentation is available, which can be useful for future developers/users:
1) Communication_protocol.doc is adescription of communication protocol between DS and PSC
2) DSP_SW_R4_User_Documentation English.doc is a description of PSI Power Supply Controller (all registers and their meaning, meaning of leds, etc)
3) Messages_Codes_en.xls explains meaning of error codes from PSC


Class Inheritance:

• Tango::Device_4Impl
• PSI_PSCIP2

Detailed documentation describing hardware used is provided with the PSCIP Linux Device Driver.

Commands, attributes and properties detailed description.

The following symbols are used:

In most of the cases the default values of 'offset' and 'current factor' should be set:

o = 0

f = 1

Change of the default setting should be done only in the case User knows what he/she is doing !!!!

Attributes:

Properties:

Commands:

Class Description:

• Device description.
• Properties description
• States description
• Commands description
• Attributes description

Conclusion:

The device server is ready for distribution application programmers.
The author will be interested in any feedback which arise from their usage of this device server.

TANGO is an open source project hosted by :

Core and Tools : CVS repository on tango-cs project Device Servers : CVS repository on tango-ds project