ebpfcat/ethercat.py

@@ -215,7 +215,7 @@ class Packet:
     packets. We implicitly add a datagram in the front which later serves
     as an identifier for the packet.
     """
-    MAXSIZE = 1000  # maximum size we use for an EtherCAT packet
+    MAXSIZE = 1500  # maximum size we use for an EtherCAT packet
     ETHERNET_HEADER = 14
     PACKET_HEADER = 16
     DATAGRAM_HEADER = 10
@@ -236,8 +236,15 @@ class Packet:
         Depending on the command, one or two more parameters represent the
         address, either terminal and offset for position or node addressing,
         or one value for logical addressing."""
+        newsize = self.size + len(data) + self.DATAGRAM_HEADER \
+                  + self.DATAGRAM_TAIL
+        if newsize > self.MAXSIZE:
+            raise OverflowError("ethercat packet size too big")
+        elif len(self.data) > 14:
+            raise OverflowError("Too many datagrams per packet")
+
         self.data.append((cmd, data, idx) + address)
-        self.size += len(data) + self.DATAGRAM_HEADER + self.DATAGRAM_TAIL
+        self.size = newsize
 
     def assemble(self, index):
         """Assemble the datagrams into a packet
@@ -306,17 +313,24 @@ class EtherCat(Protocol):
         to be sent from a queue, packs them in a packet and ships them
         out. """
         try:
-            packet = Packet()
             dgrams = []
+            packet = Packet()
+            sent = True
             while True:
-                *dgram, future = await self.send_queue.get()
-                lastsize = packet.size
-                packet.append(*dgram)
-                dgrams.append((lastsize + 10, packet.size - 2, future))
-                if packet.full() or self.send_queue.empty():
-                    ensure_future(self.process_packet(dgrams, packet))
-                    dgrams = []
-                    packet = Packet()
+                if sent:
+                   *dgram, future = await self.send_queue.get()
+                try:
+                   lastsize = packet.size
+                   packet.append(*dgram)
+                   dgrams.append((lastsize + 10, packet.size - 2, future))
+                   sent = True
+                   if not self.send_queue.empty():
+                       continue
+                except OverflowError:
+                    sent = False
+                ensure_future(self.process_packet(dgrams, packet))
+                dgrams = []
+                packet = Packet()
         except CancelledError:
             raise
         except Exception:
@@ -805,10 +819,12 @@ class Terminal:
                         index, subindex, data)
                 type, data = await self.mbx_recv()
             if type is not MBXType.COE:
-                raise EtherCatError(f"expected CoE, got {type}, {data} {odata} {index:x} {subindex}")
+                raise EtherCatError(f"expected CoE, got {type}, {data} "
+                                    f"{odata} {index:x}:{subindex:x}")
             coecmd, sdocmd, idx, subidx = unpack("<HBHB", data[:6])
             if idx != index or subindex != subidx:
-                raise EtherCatError(f"requested index {index}, got {idx}")
+                raise EtherCatError(f"requested index {index:x}:{subindex:x}, "
+                                    f"got {idx:x}:{subidx:x}")
             if coecmd >> 12 != CoECmd.SDORES.value:
                 raise EtherCatError(f"expected CoE SDORES, got {coecmd>>12:x}")
         else:

ebpfcat/terminals.py

@@ -130,7 +130,7 @@ class EK1814(EBPFTerminal):
 class EL5042(EBPFTerminal):
     compatibility = {(2, 330444882)}
     class Channel(Struct):
-        position = ProcessDesc(0x6000, 0x11)
+        position = ProcessDesc(0x6000, 0x11, 'q')
         warning = ProcessDesc(0x6000, 1)
         error = ProcessDesc(0x6000, 2)
         status = ProcessDesc(0x6000, 1, "H")
@@ -199,7 +199,11 @@ class TurboVac(EBPFTerminal):
 
 class Inficon(EBPFTerminal):
     compatibility = {(0x644, 0x21)}
+    valid = ProcessDesc(0xF640, 1)
+    overrange = ProcessDesc(0xF640, 2)
+    underrange = ProcessDesc(0xF640, 3)
     value = ProcessDesc(0xF640, 0x11, "f")
+    sensorNo = ProcessDesc(0xF640, 0x12, "f")
 
 
 class Bronkhorst(EBPFTerminal):