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Packets

A HSMS packet :class:`secsgem.hsms.packets.HsmsPacket` consists of a header :class:`secsgem.hsms.packets.HsmsHeader` and a data part represented by a string. The string contains the additional data encoded as ASCII characters for transmission over TCP. The additional data is only required for a stream/function packet.

>>> secsgem.hsms.packets.HsmsPacket(secsgem.hsms.packets.HsmsLinktestReqHeader(2))
secsgem.hsms.packets.HsmsPacket({'header': secsgem.hsms.packets.HsmsLinktestReqHeader({'function': 0, 'stream': 0, 'pType': 0, 'system': 2, 'sessionID': 65535, 'requireResponse': False, 'sType': 5}), 'data': ''})

Every header has a system id to match the response to a certain request. The system id is the first parameter to the headers constructor. The connection keeps track of the system id, a new one can be requested with the :func:`secsgem.hsms.connections.HsmsConnection.get_next_system_counter` function.

HSMS packet objects can encode themselves with the :func:`secsgem.hsms.packets.HsmsPacket.encode` function to a string, which can be sent over the TCP connection.

>>> packet = secsgem.hsms.packets.HsmsPacket(secsgem.hsms.packets.HsmsLinktestReqHeader(2))
>>> secsgem.common.format_hex(packet.encode())
'00:00:00:0a:ff:ff:00:00:00:05:00:00:00:02'

The other way around, a HSMS packet object can be created from the ASCII string with the :func:`secsgem.hsms.packets.HsmsPacket.decode` function.

>>> secsgem.hsms.packets.HsmsPacket.decode(packetData)
secsgem.hsms.packets.HsmsPacket({'header': secsgem.hsms.packets.HsmsHeader({'function': 0, 'stream': 0, 'pType': 0, 'system': 2, 'sessionID': 65535, 'requireResponse': False, 'sType': 5}), 'data': ''})

There are classes inherited from :class:`secsgem.hsms.packets.HsmsHeader` for all HSMS packet types available:

Type Class SType
Select Request :class:`secsgem.hsms.packets.HsmsSelectReqHeader` 1
Select Response :class:`secsgem.hsms.packets.HsmsSelectRspHeader` 2
Deselect Request :class:`secsgem.hsms.packets.HsmsDeselectReqHeader` 3
Deselect Response :class:`secsgem.hsms.packets.HsmsDeselectRspHeader` 4
Linktest Request :class:`secsgem.hsms.packets.HsmsLinktestReqHeader` 5
Linktest Response :class:`secsgem.hsms.packets.HsmsLinktestRspHeader` 6
Reject Request :class:`secsgem.hsms.packets.HsmsRejectReqHeader` 7
Separate Request :class:`secsgem.hsms.packets.HsmsSeparateReqHeader` 9
Data Message :class:`secsgem.hsms.packets.HsmsStreamFunctionHeader` 0

Select Request

Establish HSMS communication

>>> secsgem.hsms.packets.HsmsSelectReqHeader(14)
secsgem.hsms.packets.HsmsSelectReqHeader({'function': 0, 'stream': 0, 'pType': 0, 'system': 14, 'sessionID': 65535, 'requireResponse': False, 'sType': 1})

Select Response

Result of select request

>>> secsgem.hsms.packets.HsmsSelectRspHeader(24)
secsgem.hsms.packets.HsmsSelectRspHeader({'function': 0, 'stream': 0, 'pType': 0, 'system': 24, 'sessionID': 65535, 'requireResponse': False, 'sType': 2})

Deselect Request

Grateful close HSMS communication before disconnecting

>>> secsgem.hsms.packets.HsmsDeselectReqHeader(1)
secsgem.hsms.packets.HsmsDeselectReqHeader({'function': 0, 'stream': 0, 'pType': 0, 'system': 1, 'sessionID': 65535, 'requireResponse': False, 'sType': 3})

Deselect Response

Result of deselect request

>>> secsgem.hsms.packets.HsmsDeselectRspHeader(1)
secsgem.hsms.packets.HsmsDeselectRspHeader({'function': 0, 'stream': 0, 'pType': 0, 'system': 1, 'sessionID': 65535, 'requireResponse': False, 'sType': 4})

Linktest Request

Check the HSMS connection link is good

>>> secsgem.hsms.packets.HsmsLinktestReqHeader(2)
secsgem.hsms.packets.HsmsLinktestReqHeader({'function': 0, 'stream': 0, 'pType': 0, 'system': 2, 'sessionID': 65535, 'requireResponse': False, 'sType': 5})

Linktest Response

Result of linktest request

>>> secsgem.hsms.packets.HsmsLinktestRspHeader(10)
secsgem.hsms.packets.HsmsLinktestRspHeader({'function': 0, 'stream': 0, 'pType': 0, 'system': 10, 'sessionID': 65535, 'requireResponse': False, 'sType': 6})

Reject Request

Response to unsupported HSMS message

>>> secsgem.hsms.packets.HsmsRejectReqHeader(17, 3, 4)
secsgem.hsms.packets.HsmsRejectReqHeader({'function': 4, 'stream': 3, 'pType': 0, 'system': 17, 'sessionID': 65535, 'requireResponse': False, 'sType': 7})

Separate Request

Immediate termination of the HSMS connection

>>> secsgem.hsms.packets.HsmsSeparateReqHeader(17)
secsgem.hsms.packets.HsmsSeparateReqHeader({'function': 0, 'stream': 0, 'pType': 0, 'system': 17, 'sessionID': 65535, 'requireResponse': False, 'sType': 9})

Data Message

Secs stream and function message

>>> secsgem.hsms.packets.HsmsStreamFunctionHeader(22, 1, 1, True, 100)
secsgem.hsms.packets.HsmsStreamFunctionHeader({'function': 1, 'stream': 1, 'pType': 0, 'system': 22, 'sessionID': 100, 'requireResponse': True, 'sType': 0})