Variables¶

SECS defines a few types to transmit data in.

Data Type	Class	Code
List	`secsgem.secs.variables.SecsVarArray`	L
List	`secsgem.secs.variables.SecsVarList`	L
Binary	`secsgem.secs.variables.SecsVarBinary`	B
Boolean	`secsgem.secs.variables.SecsVarBoolean`	TF
ASCII	`secsgem.secs.variables.SecsVarString`	A
8-Byte integer	`secsgem.secs.variables.SecsVarI8`	I8
1-Byte integer	`secsgem.secs.variables.SecsVarI1`	I1
2-Byte integer	`secsgem.secs.variables.SecsVarI2`	I2
4-Byte integer	`secsgem.secs.variables.SecsVarI4`	I4
8-Byte float	`secsgem.secs.variables.SecsVarF8`	F8
4-Byte float	`secsgem.secs.variables.SecsVarF4`	F8
8-Byte unsigned integer	`secsgem.secs.variables.SecsVarU8`	U8
1-Byte unsigned integer	`secsgem.secs.variables.SecsVarU1`	U1
2-Byte unsigned integer	`secsgem.secs.variables.SecsVarU2`	U2
4-Byte unsigned integer	`secsgem.secs.variables.SecsVarU4`	U4

Example:

>>> secsgem.SecsVarString(value="TESTString")
A 'TESTString'
>>> secsgem.SecsVarBoolean(value=True)
TF True
>>> secsgem.SecsVarU4(value=1337)
U4 1337

Type arrays¶

The numeric types can also be an array of that type:

>>> secsgem.SecsVarU1(value=[1, 2, 3, 4])
U1 [1, 2, 3, 4]
>>> secsgem.SecsVarBoolean(value=[True, False, False, True])
TF [True, False, False, True]

The length of this array can be fixed with the length parameter:

>>> secsgem.SecsVarU1(length=3, value=[1, 2, 3])
U1 [1, 2, 3]
>>> secsgem.SecsVarU1(length=3, value=[1, 2, 3, 4])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/bparzella/Developer/secsgem/secsgem/secs/variables.py", line 1694, in __init__
    self.set(value)
  File "/Users/bparzella/Developer/secsgem/secsgem/secs/variables.py", line 1716, in set
    raise ValueError("Value longer than {} chars".format(self.length))
ValueError: Value longer than 3 chars

>>> secsgem.SecsVarString(length=3, value="Hello").get()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/bparzella/Developer/secsgem/secsgem/secs/variables.py", line 776, in __init__
    self.set(value)
  File "/Users/bparzella/Developer/secsgem/secsgem/secs/variables.py", line 794, in set
    raise ValueError("Value longer than {} chars".format(self.length))
ValueError: Value longer than 3 chars

Getting data¶

The data can be accessed with the secsgem.secs.variables.SecsVarU1.get() method, arrays can be accessed using the index operator:

>>> secsgem.SecsVarU1(value=1).get()
1
>>> secsgem.SecsVarU1(length=3, value=[1, 2, 3]).get()
[1, 2, 3]
>>> secsgem.SecsVarU1(value=1)[0]
1
>>> secsgem.SecsVarU1(length=3, value=[1, 2, 3])[1]
2

Setting data¶

The data can be set with the secsgem.secs.variables.SecsVarString.set() method, arrays can be updated using the index operator:

>>> v=secsgem.SecsVarU1(length=3, value=[1, 2, 3])
>>> v.set([3, 2, 1])
>>> v
U1 [3, 2, 1]
>>> v[0] = 1
>>> v
U1 [1, 2, 1]

En-/Decoding¶

The variable types can secsgem.secs.variables.SecsVarArray.encode() and secsgem.secs.variables.SecsVarString.decode() themselves to ASCII data transferrable with the HSMS protocol:

>>> v=secsgem.SecsVarString(value="Hello")
>>> d=v.encode()
>>> d
'A\x05Hello'
>>> secsgem.format_hex(d)
'41:05:48:65:6c:6c:6f'
>>> v.set("NewText")
>>> v
A 'NewText'
>>> v.decode(d)
7
>>> v
A 'Hello'

SecsVarArray¶

secsgem.secs.variables.SecsVarArray is a special type for a list of the same type. The items of the array can be accessed with the index operator.

>>> v=secsgem.SecsVarArray(secsgem.SecsVarU4(1))
>>> v.set([1, 2, 3])
>>> v
[U4 1, U4 2, U4 3]
>>> v.get()
[1, 2, 3]
>>> v[1]
2

A new item can be appended to the array with the secsgem.secs.variables.SecsVarArray.append() method.

SecsVarList¶

secsgem.secs.variables.SecsVarList is a special type for a list of the different types. The items of the list can be accessed like properties of the object.

An ordered dictionary is required for the creation, because pythons default dictionary will be randomly sorted. Sorting is essential because both peers need to have the data in the same order.

>>> v=secsgem.SecsVarList(OrderedDict((
...         ("var1", secsgem.SecsVarU4(1)),
...         ("var2", secsgem.SecsVarString()),
...     )), 2)
>>> v.var1=3
>>> v.var2="Hallo"
>>> v
[var1: U4 3, var2: A 'Hallo']
>>> v.var2
'Hallo'
>>> secsgem.format_hex(v.encode())
'01:02:b1:04:00:00:00:03:41:05:48:61:6c:6c:6f'

SecsVarDynamic¶

secsgem.secs.variables.SecsVarDynamic can take different types, if specified to a certain set of types.

>>> v=secsgem.SecsVarDynamic([secsgem.SecsVarString, secsgem.SecsVarU1])
>>> v.set(secsgem.SecsVarString(value="Hello"))
>>> v
A 'Hello'
>>> v.set(secsgem.SecsVarU1(value=10))
>>> v
U1 10
>>> v.set(secsgem.SecsVarU4(value=10))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/bparzella/Developer/secsgem/secsgem/secs/variables.py", line 176, in set
    raise ValueError("Unsupported type {} for this instance of SecsVarDynamic, allowed {}".format(value.__class__.__name__, self.types))
ValueError: Unsupported type SecsVarU4 for this instance of SecsVarDynamic, allowed [<class 'secsgem.secs.variables.SecsVarString'>, <class 'secsgem.secs.variables.SecsVarU1'>]