diff --git a/src/common.rs b/src/common.rs
index f64a289d9c192138cca32e3d48dabe45fab72302..21f3d91b2c6977da112626c46870f0687e451248 100644
--- a/src/common.rs
+++ b/src/common.rs
@@ -112,6 +112,11 @@ impl From<Id> for ProtoComponentId {
         Self(id)
     }
 }
+impl From<&[u8]> for Payload {
+    fn from(s: &[u8]) -> Payload {
+        Payload(Arc::new(s.to_vec()))
+    }
+}
 impl Payload {
     pub fn new(len: usize) -> Payload {
         let mut v = Vec::with_capacity(len);
diff --git a/src/runtime/communication.rs b/src/runtime/communication.rs
index 0b3d617a931edbbd4ee660bfcace2562c46801bc..839cc539d37d3e5071e143f6af6f952206b034a6 100644
--- a/src/runtime/communication.rs
+++ b/src/runtime/communication.rs
@@ -85,6 +85,26 @@ impl SyncProtoContext<'_> {
 }
 
 impl Connector {
+    pub fn put(&mut self, port: PortId, payload: Payload) -> Result<(), PortOpError> {
+        use PortOpError::*;
+        if !self.native_ports.contains(&port) {
+            return Err(PortUnavailable);
+        }
+        if Putter != *self.port_info.polarities.get(&port).unwrap() {
+            return Err(WrongPolarity);
+        }
+        match &mut self.phased {
+            ConnectorPhased::Setup { .. } => Err(NotConnected),
+            ConnectorPhased::Communication { native_batches, .. } => {
+                let batch = native_batches.last_mut().unwrap();
+                if batch.to_put.contains_key(&port) {
+                    return Err(MultipleOpsOnPort);
+                }
+                batch.to_put.insert(port, payload);
+                Ok(())
+            }
+        }
+    }
     pub fn sync(&mut self) -> Result<usize, SyncError> {
         use SyncError::*;
         match &mut self.phased {
diff --git a/src/runtime/error.rs b/src/runtime/error.rs
index 672a3d6554cb00feecfe4579beed4fbe9111c55b..7de8323c2e0d468fbcf03a6b55ef1b8dd1d0b437 100644
--- a/src/runtime/error.rs
+++ b/src/runtime/error.rs
@@ -19,3 +19,10 @@ pub enum SyncError {
     InconsistentProtoComponent(ProtoComponentId),
     IndistinguishableBatches([usize; 2]),
 }
+#[derive(Debug)]
+pub enum PortOpError {
+    WrongPolarity,
+    NotConnected,
+    MultipleOpsOnPort,
+    PortUnavailable,
+}
diff --git a/src/runtime/my_tests.rs b/src/runtime/my_tests.rs
index d59d4007dfae04c3bb2d03a627ca054e9c4d495e..d702b34971338a724d540e61cbbae627f120e604 100644
--- a/src/runtime/my_tests.rs
+++ b/src/runtime/my_tests.rs
@@ -88,3 +88,28 @@ fn multithreaded_connect() {
     })
     .unwrap();
 }
+
+#[test]
+fn put_no_sync() {
+    let mut c = Connector::new_simple(MINIMAL_PROTO.clone(), 0);
+    let [o, _] = c.new_port_pair();
+    c.connect(Duration::from_secs(1)).unwrap();
+    c.put(o, (b"hi" as &[_]).into()).unwrap();
+}
+
+#[test]
+fn wrong_polarity_bad() {
+    let mut c = Connector::new_simple(MINIMAL_PROTO.clone(), 0);
+    let [_, i] = c.new_port_pair();
+    c.connect(Duration::from_secs(1)).unwrap();
+    c.put(i, (b"hi" as &[_]).into()).unwrap_err();
+}
+
+#[test]
+fn dup_put_bad() {
+    let mut c = Connector::new_simple(MINIMAL_PROTO.clone(), 0);
+    let [o, _] = c.new_port_pair();
+    c.connect(Duration::from_secs(1)).unwrap();
+    c.put(o, (b"hi" as &[_]).into()).unwrap();
+    c.put(o, (b"hi" as &[_]).into()).unwrap_err();
+}