Add functions to read target setpoints

Also provide a mechanism to set actual position and velocity in the
internal data. These data will be requested periodically by the driver.

schunk_egu_egk_gripper_dummy/src/dummy.py

@@ -4,6 +4,7 @@
 from pathlib import Path
 import json
 import string
+import struct
 
 
 class Dummy(object):
@@ -20,6 +21,8 @@ def __init__(self):
         self.diagnostics_byte = 15
         self.reserved_status_bits = [10, 15] + list(range(18, 31))
         self.reserved_control_bits = [10, 15] + list(range(17, 30))
+        self.actual_position = "0x0230"
+        self.actual_speed = "0x0238"
 
         enum_config = os.path.join(
             Path(__file__).resolve().parents[1], "config/enum.json"
@@ -171,6 +174,20 @@ def get_control_bit(self, bit: int) -> int | bool:
         byte_index, bit_index = divmod(bit, 8)
         return 1 if self.plc_output_buffer[byte_index] & (1 << bit_index) != 0 else 0
 
+    def get_target_position(self) -> float:
+        return struct.unpack("f", self.plc_output_buffer[4:8])[0]
+
+    def get_target_speed(self) -> float:
+        return struct.unpack("f", self.plc_output_buffer[8:12])[0]
+
+    def set_actual_position(self, position: float) -> None:
+        self.data[self.actual_position] = [
+            bytes(struct.pack("f", position)).hex().upper()
+        ]
+
+    def set_actual_speed(self, speed: float) -> None:
+        self.data[self.actual_speed] = [bytes(struct.pack("f", speed)).hex().upper()]
+
     def process_control_bits(self) -> None:
 
         # Acknowledge

schunk_egu_egk_gripper_dummy/tests/test_plc_communication.py

@@ -1,4 +1,6 @@
 from src.dummy import Dummy
+import struct
+import pytest
 
 # [1]: https://stb.cloud.schunk.com/media/IM0046706.PDF
 
@@ -94,3 +96,37 @@ def test_dummy_rejects_reading_reserved_control_bits():
     for bit in dummy.reserved_control_bits:
         assert isinstance(dummy.get_control_bit(bit), bool)  # call fails
         assert not dummy.get_control_bit(bit)
+
+
+def test_dummy_supports_reading_target_position():
+    dummy = Dummy()
+    target_pos = 0.0123
+    dummy.plc_output_buffer[4:8] = bytes(struct.pack("f", target_pos))
+    assert pytest.approx(dummy.get_target_position()) == target_pos
+
+
+def test_dummy_supports_reading_target_speed():
+    dummy = Dummy()
+    target_speed = 55.3
+    dummy.plc_output_buffer[8:12] = bytes(struct.pack("f", target_speed))
+    assert pytest.approx(dummy.get_target_speed()) == target_speed
+
+
+def test_dummy_supports_writing_actual_position():
+    dummy = Dummy()
+    inst = "0x0230"  # <actual_pos>
+    pos = 0.123
+    dummy.set_actual_position(pos)
+    read_pos = dummy.data[inst][0]
+    read_pos = struct.unpack("f", bytes.fromhex(read_pos))[0]
+    assert pytest.approx(read_pos) == pos
+
+
+def test_dummy_supports_writing_actual_speed():
+    dummy = Dummy()
+    inst = "0x0238"  # <actual_vel>
+    speed = 66.5
+    dummy.set_actual_speed(speed)
+    read_speed = dummy.data[inst][0]
+    read_speed = struct.unpack("f", bytes.fromhex(read_speed))[0]
+    assert pytest.approx(read_speed) == speed