diff --git a/org.lflang.tests/src/org/lflang/tests/compiler/RoundTripTests.java b/org.lflang.tests/src/org/lflang/tests/compiler/RoundTripTests.java
index bcc4f0ac0a..d1ea81e5be 100644
--- a/org.lflang.tests/src/org/lflang/tests/compiler/RoundTripTests.java
+++ b/org.lflang.tests/src/org/lflang/tests/compiler/RoundTripTests.java
@@ -1,5 +1,9 @@
 package org.lflang.tests.compiler;
 
+import static java.util.Collections.emptyList;
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.MatcherAssert.assertThat;
+
 import java.nio.file.Files;
 import java.nio.file.Path;
 
@@ -36,12 +40,13 @@ public void roundTripTest() throws Exception {
 
     private void run(Path file) throws Exception {
         Model originalModel = LfParsingUtil.parse(file);
-        Assertions.assertTrue(originalModel.eResource().getErrors().isEmpty());
+        assertThat(originalModel.eResource().getErrors(), equalTo(emptyList()));
         // TODO: Check that the output is a fixed point
         final int smallLineLength = 20;
         final String squishedTestCase = FormattingUtils.render(originalModel, smallLineLength);
         final Model resultingModel = LfParsingUtil.parseSourceAsIfInDirectory(file.getParent(), squishedTestCase);
 
+        assertThat(resultingModel.eResource().getErrors(), equalTo(emptyList()));
         Assertions.assertTrue(
             new IsEqual(originalModel).doSwitch(resultingModel),
             String.format(
diff --git a/org.lflang/src/lib/rs/reactor-rs b/org.lflang/src/lib/rs/reactor-rs
index bef9d10abd..98991f3c3c 160000
--- a/org.lflang/src/lib/rs/reactor-rs
+++ b/org.lflang/src/lib/rs/reactor-rs
@@ -1 +1 @@
-Subproject commit bef9d10abde77dc95336cba8cda18032070aba15
+Subproject commit 98991f3c3ce360cfc67511103bb58511f6faba06
diff --git a/org.lflang/src/lib/rs/runtime-version.properties b/org.lflang/src/lib/rs/runtime-version.properties
index 6668771240..66b91bb698 100644
--- a/org.lflang/src/lib/rs/runtime-version.properties
+++ b/org.lflang/src/lib/rs/runtime-version.properties
@@ -1 +1 @@
-rs = bef9d10abde77dc95336cba8cda18032070aba15
+rs = 98991f3c3ce360cfc67511103bb58511f6faba06
diff --git a/org.lflang/src/org/lflang/generator/rust/PortEmitter.kt b/org.lflang/src/org/lflang/generator/rust/PortEmitter.kt
index 9544e8c4ab..5567b7b12c 100644
--- a/org.lflang/src/org/lflang/generator/rust/PortEmitter.kt
+++ b/org.lflang/src/org/lflang/generator/rust/PortEmitter.kt
@@ -62,8 +62,25 @@ object PortEmitter : RustEmitterBase() {
         val self = "&mut __self.$rustFieldName"
         val child = "&mut $rustChildName.$rustFieldOnChildName"
 
-        return if (isInput) "$assembler.bind_ports($self, $child)?;"
-        else "$assembler.bind_ports($child, $self)?;"
+        return if (isGeneratedAsMultiport) {
+            var lhsPorts = "$child.iter_mut()"
+            var rhsPorts = "$self.iter_mut()"
+
+            if (isContainedInBank && !isMultiport) {
+                lhsPorts = "unsafe_iter_bank!($rustChildName # $rustFieldOnChildName)"
+            } else if (isContainedInBank && isMultiport) {
+                lhsPorts = "unsafe_iter_bank!($rustChildName # ($rustFieldOnChildName)+)"
+            }
+
+            if (isInput) {
+                lhsPorts = rhsPorts.also { rhsPorts = lhsPorts }
+            }
+
+            "$assembler.bind_ports_zip($lhsPorts, $rhsPorts)?;"
+        } else {
+            if (isInput) "$assembler.bind_ports($self, $child)?;"
+            else "$assembler.bind_ports($child, $self)?;"
+        }
     }
 
     /**
@@ -91,9 +108,9 @@ object PortEmitter : RustEmitterBase() {
         val container: Instantiation? = container
         val port = PortData.from(variable as Port)
 
-        if (container?.isBank == true && port.isMultiport && isInterleaved) {
+        if (container?.isBank == true && port.isGeneratedAsMultiport && isInterleaved) {
             return "unsafe_iter_bank!(${container.name} # interleaved(${port.rustFieldName}))"
-        } else if (container?.isBank == true && port.isMultiport) {
+        } else if (container?.isBank == true && port.isGeneratedAsMultiport) {
             return "unsafe_iter_bank!(${container.name} # (${port.rustFieldName})+)"
         } else if (container?.isBank == true) {
             return "unsafe_iter_bank!(${container.name} # ${port.rustFieldName})"
@@ -102,7 +119,7 @@ object PortEmitter : RustEmitterBase() {
         // todo this is missing some tests where we try to borrow several multiports from same reactor
         val ref = (container?.name ?: "__self") + "." + port.rustFieldName
 
-        return if (port.isMultiport) {
+        return if (port.isGeneratedAsMultiport) {
             "$ref.iter_mut()"
         } else {
             "std::iter::once(&mut $ref)"
diff --git a/org.lflang/src/org/lflang/generator/rust/RustModel.kt b/org.lflang/src/org/lflang/generator/rust/RustModel.kt
index 6bf21b5b3e..943bcf3f33 100644
--- a/org.lflang/src/org/lflang/generator/rust/RustModel.kt
+++ b/org.lflang/src/org/lflang/generator/rust/RustModel.kt
@@ -25,17 +25,8 @@
 
 package org.lflang.generator.rust
 
-import org.lflang.ASTUtils
-import org.lflang.AttributeUtils
-import org.lflang.ErrorReporter
-import org.lflang.IDENT_REGEX
-import org.lflang.InferredType
-import org.lflang.TargetConfig
+import org.lflang.*
 import org.lflang.TargetProperty.BuildType
-import org.lflang.TimeUnit
-import org.lflang.TimeValue
-import org.lflang.allComponents
-import org.lflang.camelToSnakeCase
 import org.lflang.generator.*
 import org.lflang.inBlock
 import org.lflang.indexInContainer
@@ -44,31 +35,11 @@ import org.lflang.isBank
 import org.lflang.isInput
 import org.lflang.isLogical
 import org.lflang.isMultiport
-import org.lflang.lf.Action
-import org.lflang.lf.BuiltinTrigger
-import org.lflang.lf.BuiltinTriggerRef
-import org.lflang.lf.Code
-import org.lflang.lf.Connection
-import org.lflang.lf.Expression
-import org.lflang.lf.Input
-import org.lflang.lf.Instantiation
-import org.lflang.lf.Literal
-import org.lflang.lf.ParameterReference
-import org.lflang.lf.Port
-import org.lflang.lf.Reaction
-import org.lflang.lf.Reactor
-import org.lflang.lf.Time
+import org.lflang.lf.*
 import org.lflang.lf.Timer
-import org.lflang.lf.TypeParm
-import org.lflang.lf.VarRef
-import org.lflang.lf.Variable
-import org.lflang.lf.WidthSpec
-import org.lflang.reactor
-import org.lflang.toPath
-import org.lflang.toText
-import org.lflang.toTimeValue
 import java.nio.file.Path
 import java.util.*
+import kotlin.text.capitalize
 
 private typealias Ident = String
 const val PARALLEL_RT_FEATURE = "parallel-runtime"
@@ -218,12 +189,18 @@ data class ChildPortReference(
     override val lfName: Ident,
     override val isInput: Boolean,
     override val dataType: TargetCode,
-    override val isMultiport: Boolean
+    val widthSpecMultiport: TargetCode?,
+    val widthSpecChild: TargetCode?,
 ) : PortLike() {
+    override val isMultiport: Boolean
+        get() = widthSpecMultiport != null
+    override val isContainedInBank: Boolean get() = widthSpecChild != null
     val rustFieldOnChildName: String = lfName.escapeRustIdent()
 
     /** Sync with [NestedReactorInstance.rustLocalName]. */
     val rustChildName: TargetCode = childLfName.escapeRustIdent()
+
+    val widthParamName: TargetCode = (rustFieldName + "__width").escapeRustIdent()
 }
 
 /**
@@ -380,7 +357,10 @@ sealed class PortLike : ReactorComponent() {
     abstract val isInput: Boolean
 
     abstract val dataType: TargetCode
+    val isGeneratedAsMultiport: Boolean
+        get() = isMultiport || isContainedInBank
     abstract val isMultiport: Boolean
+    abstract val isContainedInBank: Boolean
 }
 
 /**
@@ -395,6 +375,7 @@ data class PortData(
     val widthSpec: TargetCode?,
 ) : PortLike() {
     override val isMultiport: Boolean get() = widthSpec != null
+    override val isContainedInBank = false
 
     companion object {
         fun from(port: Port) =
@@ -574,7 +555,8 @@ object RustModelBuilder {
                                 lfName = variable.name,
                                 isInput = variable is Input,
                                 dataType = container.reactor.instantiateType(formalType, it.container.typeParms),
-                                isMultiport = variable.isMultiport
+                                widthSpecMultiport = variable.widthSpec?.toRustExpr(),
+                                widthSpecChild = container.widthSpec?.toRustExpr(),
                             )
                         } else {
                             components[variable.name] ?: throw UnsupportedGeneratorFeatureException(
diff --git a/org.lflang/src/org/lflang/generator/rust/RustReactorEmitter.kt b/org.lflang/src/org/lflang/generator/rust/RustReactorEmitter.kt
index 50b5a3c2b2..46be14327e 100644
--- a/org.lflang/src/org/lflang/generator/rust/RustReactorEmitter.kt
+++ b/org.lflang/src/org/lflang/generator/rust/RustReactorEmitter.kt
@@ -28,7 +28,6 @@ import org.lflang.*
 import org.lflang.generator.PrependOperator
 import org.lflang.generator.PrependOperator.rangeTo
 import org.lflang.generator.TargetCode
-import org.lflang.generator.UnsupportedGeneratorFeatureException
 
 
 /**
@@ -47,6 +46,8 @@ object RustReactorEmitter : RustEmitterBase() {
             val typeParams = typeParamList.map { it.targetCode }.angle()
             val typeArgs = typeParamList.map { it.lfName }.angle()
 
+            val privateParams = reactor.extraConstructionParams;
+
             with(reactor.names) {
                 with(PrependOperator) {
                     """
@@ -84,6 +85,10 @@ ${"             |       "..ctorParams.joinWithCommasLn { "${it.lfName.escapeRust
                 |   ) -> Self {
                 |       Self { __phantom: std::marker::PhantomData, ${ctorParams.joinWithCommas { it.lfName.escapeRustIdent() }} }
                 |   }
+                |}
+                |
+                |struct $privateParamStruct {
+${"             |       "..privateParams.joinWithCommasLn { "${it.ident.escapeRustIdent()}: ${it.type}" }}
                 |}
                 |
                 |//------------------------//
@@ -99,7 +104,8 @@ ${"             |    "..otherComponents.joinWithCommasLn { it.toStructField() }}
                 |    #[inline]
                 |    fn user_assemble(__assembler: &mut $rsRuntime::assembly::ComponentCreator<Self>,
                 |                     __id: $rsRuntime::ReactorId,
-                |                     __params: $paramStructName$typeArgs) -> $rsRuntime::assembly::AssemblyResult<Self> {
+                |                     __params: $paramStructName$typeArgs,
+                |                     $privateParamsVarName: $privateParamStruct) -> $rsRuntime::assembly::AssemblyResult<Self> {
                 |        let $ctorParamsDeconstructor = __params;
                 |
                 |        let __impl = {
@@ -174,9 +180,26 @@ ${"             |        "..otherComponents.mapNotNull { it.cleanupAction() }.jo
                 "__ctx.with_child::<$type, _>(\"$lfName\", $params, |mut __ctx, $rustLocalName| {"
         }
 
+        val portRefs = this.portReferences
+        fun NestedReactorInstance.portWidthDecls(): List<TargetCode> =
+            // if we refer to some port of the child as a bank, we need to surface its width here
+            portRefs.filter { it.childLfName == this.lfName && it.isGeneratedAsMultiport }.map {
+                val portWidthExpr = if (it.isMultiport) "${it.childLfName}.${it.rustFieldOnChildName}.len()"
+                else "1" // that's a single port
+
+                // if we're in a bank, the total length is the sum
+                val sumExpr =
+                    if (it.isContainedInBank) "${it.childLfName}.iter().map(|${it.childLfName}| $portWidthExpr).sum()"
+                    else portWidthExpr
+
+                "let ${it.widthParamName} = $sumExpr;"
+            }
+
+
         return buildString {
             for (inst in nestedInstances) {
                 append(inst.childDeclaration()).append("\n")
+                inst.portWidthDecls().joinTo(this, "\n").append("\n")
             }
 
             append(assembleSelf).append("\n")
@@ -200,9 +223,13 @@ ${"             |        "..otherComponents.mapNotNull { it.cleanupAction() }.jo
         val pattern = reactionIds.joinToString(prefix = "[", separator = ", ", postfix = "]")
         val debugLabelArray = debugLabels.joinToString(", ", "[", "]")
 
+        val privateParamsCtor = extraConstructionParams.joinWithCommas(prefix = "$privateParamStruct { ", postfix = " }") {
+            it.ident.escapeRustIdent()
+        }
+
         return """
                 |__ctx.assemble_self(
-                |    |cc, id| Self::user_assemble(cc, id, $ctorParamsDeconstructor),
+                |    |cc, id| Self::user_assemble(cc, id, $ctorParamsDeconstructor, $privateParamsCtor),
                 |    // number of non-synthetic reactions
                 |    ${reactions.size},
                 |    // reaction debug labels
@@ -284,7 +311,7 @@ ${"             |        "..declareChildConnections()}
                     this += "__assembler.declare_triggers($rsRuntime::assembly::TriggerId::SHUTDOWN, ${n.invokerId})?;"
                 this += n.uses.map { trigger -> "__assembler.declare_uses(${n.invokerId}, __self.${trigger.rustFieldName}.get_id())?;" }
                 this += n.effects.filterIsInstance<PortLike>().map { port ->
-                    if (port.isMultiport) {
+                    if (port.isGeneratedAsMultiport) {
                         "__assembler.effects_multiport(${n.invokerId}, &__self.${port.rustFieldName})?;"
                     } else {
                         "__assembler.effects_port(${n.invokerId}, &__self.${port.rustFieldName})?;"
@@ -337,7 +364,7 @@ ${"             |        "..declareChildConnections()}
             if (isLogical) "$rsRuntime::LogicalAction<${dataType ?: "()"}>"
             else "$rsRuntime::PhysicalActionRef<${dataType ?: "()"}>"
         is PortLike   -> with(this) {
-            if (isMultiport) "$rsRuntime::Multiport<$dataType>"
+            if (isGeneratedAsMultiport) "$rsRuntime::Multiport<$dataType>"
             else "$rsRuntime::Port<$dataType>"
         }
         is TimerData  -> "$rsRuntime::Timer"
@@ -360,8 +387,8 @@ ${"             |        "..declareChildConnections()}
             }
         }
         is ChildPortReference -> {
-            if (isMultiport) {
-                throw UnsupportedGeneratorFeatureException("Multiport references from parent reactor")
+            if (isGeneratedAsMultiport) {
+                "__assembler.new_multiport::<$dataType>(\"$childLfName.$lfName\", $portKind, $privateParamsVarName.$widthParamName)?"
             } else {
                 "__assembler.new_port::<$dataType>(\"$childLfName.$lfName\", $portKind)"
             }
@@ -421,7 +448,7 @@ ${"             |        "..declareChildConnections()}
             if (isLogical) "ctx.cleanup_logical_action(&mut self.$rustFieldName);"
             else "ctx.cleanup_physical_action(&mut self.$rustFieldName);"
         is PortLike           ->
-            if (isMultiport) "ctx.cleanup_multiport(&mut self.$rustFieldName);"
+            if (isGeneratedAsMultiport) "ctx.cleanup_multiport(&mut self.$rustFieldName);"
             else "ctx.cleanup_port(&mut self.$rustFieldName);"
         else                  -> null
     }
@@ -457,5 +484,34 @@ ${"             |    "..body}
         }
     }
 
+    /**
+     * A list of parameters that are required for construction
+     * but are of internal use to the generator.
+     * The widths of port banks referred to by a reactor are
+     * saved in here, so that we use the actual runtime value.
+     */
+    private val ReactorInfo.extraConstructionParams: List<PrivateParamSpec>
+        get() {
+            val result = mutableListOf<PrivateParamSpec>()
+
+            for (ref in this.portReferences) {
+                if (ref.isGeneratedAsMultiport) {
+                    result += PrivateParamSpec(
+                        ident = ref.widthParamName,
+                        type = "usize"
+                    )
+                }
+            }
+
+            return result
+        }
+
+    private data class PrivateParamSpec(
+        val ident: String,
+        val type: TargetCode
+    )
+
+    private const val privateParamStruct: String = "PrivateParams"
 
+    private const val privateParamsVarName = "__more_params"
 }
diff --git a/test/Rust/src/multiport/ReadOutputOfContainedBank.lf b/test/Rust/src/multiport/ReadOutputOfContainedBank.lf
new file mode 100644
index 0000000000..80103366db
--- /dev/null
+++ b/test/Rust/src/multiport/ReadOutputOfContainedBank.lf
@@ -0,0 +1,48 @@
+// Test reacting to and reading outputs from a contained reactor bank in various
+// permutations.
+target Rust
+
+reactor Contained(bank_index: usize(0)) {
+    state bank_index(bank_index)
+
+    output out: usize
+
+    reaction(startup) -> out {= ctx.set(out, 42 * self.bank_index); =}
+}
+
+main reactor {
+    c = new[4] Contained()
+    state count: usize(0)
+
+    reaction(startup) c.out {=
+        for (i, chan) in c__out.iter().enumerate() {
+            let result = ctx.get(chan).unwrap();
+            println!("Startup reaction reading output of contained reactor: {}", result);
+            assert_eq!(result, 42 * i);
+        }
+        self.count += 1;
+    =}
+
+    reaction(c.out) {=
+        for (i, chan) in c__out.iter().enumerate() {
+            let result = ctx.get(chan).unwrap();
+            println!("Reading output of contained reactor: {}", result);
+            assert_eq!(result, 42 * i);
+        }
+        self.count += 1;
+    =}
+
+    reaction(startup, c.out) {=
+        for (i, chan) in c__out.iter().enumerate() {
+            let result = ctx.get(chan).unwrap();
+            println!("Alternate triggering reading output of contained reactor: {}", result);
+            assert_eq!(result, 42 * i);
+        }
+        self.count += 1;
+    =}
+
+    reaction(shutdown) {=
+        assert_eq!(self.count, 3);
+        println!("success");
+    =}
+}
diff --git a/test/Rust/src/multiport/WidthWithParameter.lf b/test/Rust/src/multiport/WidthWithParameter.lf
new file mode 100644
index 0000000000..e32f67bec5
--- /dev/null
+++ b/test/Rust/src/multiport/WidthWithParameter.lf
@@ -0,0 +1,17 @@
+target Rust
+
+reactor Some(value: usize(30)) {
+    output[value] finished: unit
+
+    reaction(startup) -> finished {=
+        for p in finished {
+            ctx.set(p, ());
+        }
+    =}
+}
+
+main reactor {
+    some = new Some(value = 20)
+
+    reaction(some.finished) {= println!("success"); =}
+}
diff --git a/test/Rust/src/multiport/WriteInputOfContainedBank.lf b/test/Rust/src/multiport/WriteInputOfContainedBank.lf
new file mode 100644
index 0000000000..cab6e80e16
--- /dev/null
+++ b/test/Rust/src/multiport/WriteInputOfContainedBank.lf
@@ -0,0 +1,30 @@
+// Test writing inputs to a contained reactor bank
+target Rust
+
+reactor Contained(bank_index: usize(0)) {
+    state bank_index(bank_index)
+
+    input inpt: usize
+    state count: usize(0)
+
+    reaction(inpt) {=
+        let result = ctx.get(inpt).unwrap();
+        println!("Instance {} received {}", self.bank_index, result);
+        assert_eq!(result, self.bank_index * 42);
+        self.count += 1;
+    =}
+
+    reaction(shutdown) {=
+        assert_eq!(self.count, 1, "One of the reactions failed to trigger");
+    =}
+}
+
+main reactor {
+    c = new[4] Contained()
+
+    reaction(startup) -> c.inpt {=
+        for i in 0..c__inpt.len() {
+            ctx.set(&mut c__inpt[i], i * 42);
+        }
+    =}
+}