Keep plc data buffers separate

This makes bit operations on these data easier than with immutable
strings.
Also add image documentation for the different plc data messages and
double words.

schunk_egu_egk_gripper_dummy/src/dummy.py

@@ -13,6 +13,8 @@ def __init__(self):
         self.enum = None
         self.metadata = None
         self.data = None
+        self.plc_input = "0x0040"
+        self.plc_output = "0x0048"
 
         enum_config = os.path.join(
             Path(__file__).resolve().parents[1], "config/enum.json"
@@ -30,6 +32,9 @@ def __init__(self):
         with open(data_config, "r") as f:
             self.data = json.load(f)
 
+        self.plc_input_buffer = bytearray(bytes.fromhex(self.data[self.plc_input][0]))
+        self.plc_output_buffer = bytearray(bytes.fromhex(self.data[self.plc_output][0]))
+
     def start(self) -> None:
         if self.running:
             return
@@ -83,6 +88,16 @@ def get_data(self, query: dict[str, str]) -> list:
                 return result
             if inst not in self.data:
                 return result
+            if inst == self.plc_input:
+                return self.get_plc_input()
+            if inst == self.plc_output:
+                return self.get_plc_output()
             return self.data[inst]
         else:
             return []
+
+    def get_plc_input(self):
+        return [self.plc_input_buffer.hex().upper()]
+
+    def get_plc_output(self):
+        return [self.plc_output_buffer.hex().upper()]

schunk_egu_egk_gripper_dummy/tests/test_plc_communication.py

@@ -0,0 +1,48 @@
+from src.dummy import Dummy
+import pytest
+
+# [1]: https://stb.cloud.schunk.com/media/IM0046706.PDF
+
+
+def test_dummy_initializes_plc_data_buffers():
+    dummy = Dummy()
+    assert dummy.data[dummy.plc_input][0] == dummy.plc_input_buffer.hex().upper()
+    assert dummy.data[dummy.plc_output][0] == dummy.plc_output_buffer.hex().upper()
+
+
+def test_dummy_returns_plc_data():
+    dummy = Dummy()
+    assert dummy.data[dummy.plc_input] == dummy.get_plc_input()
+    assert dummy.data[dummy.plc_output] == dummy.get_plc_output()
+
+
+# See p. 24 in
+# Booting and establishing operational readiness [1]
+
+
+@pytest.mark.skip()
+def test_dummy_starts_in_error_state():
+    dummy = Dummy()
+    query = {"inst": dummy.plc_input, "count": 1}
+    data = dummy.get_data(query)[0]
+    assert data[0:2] == "80"
+    assert data[30:] == "D9"  # ERR_FAST_STOP
+
+
+@pytest.mark.skip()
+def test_dummy_is_ready_after_acknowledge():
+    dummy = Dummy()
+    control_double_word = "04000000"
+    set_position = "00000000"
+    set_speed = "00000000"
+    gripping_force = "00000000"
+    command = {
+        "inst": dummy.plc_output,
+        "value": control_double_word + set_position + set_speed + gripping_force,
+    }
+    dummy.post(command)
+
+    query = {"inst": dummy.plc_input, "count": 1}
+    data = dummy.get_data(query)[0]
+    assert data[0:2] == "11"
+    assert data[30:] == "00"  # ERR_NONE