diff --git a/packages/hal/src/validators/apex/index.ts b/packages/hal/src/validators/apex/index.ts
index 463ee06..5d98c03 100644
--- a/packages/hal/src/validators/apex/index.ts
+++ b/packages/hal/src/validators/apex/index.ts
@@ -48,6 +48,11 @@ export class ApexValidator extends EventEmitter implements BillValidator {
   constructor(config: ValidatorConfig) {
     super()
     this.config = config
+    // Seed from config, as id003 effectively does by threading config.fiatCode
+    // into its rs232 config. Nothing in the app calls setFiatCode(), so a
+    // driver that relies on it alone resolves every credit channel to null and
+    // rejects every note. setFiatCode() stays available as a later override.
+    this.fiatCode = config.fiatCode ?? config.rs232.fiatCode ?? null
     this._throttledError = throttle((err: Error) => this.emit('error', err), 2000)
   }
 
@@ -76,7 +81,20 @@ export class ApexValidator extends EventEmitter implements BillValidator {
     this.fsm.on('billsAccepted', () => this.emit('billsAccepted'))
     this.fsm.on('billsRead', (bill: { denomination: number | null; code: string }) => {
       if (!bill.denomination) {
-        console.log('[APEX] Bill rejected: unsupported/unmapped channel')
+        // Say WHICH of the two causes this is. "unmapped channel" alone reads
+        // as a hardware/dataset mismatch and sent us looking at DIP switches
+        // when the real cause was a null fiat code rejecting every note.
+        if (!this.fiatCode) {
+          console.error(
+            '[APEX] Bill rejected: no fiat code set on the driver, so NO channel ' +
+              'can resolve to a value. Every note will be returned until this is fixed.'
+          )
+        } else {
+          console.log(
+            `[APEX] Bill rejected: channel ${bill.code || '?'} is not mapped in the ` +
+              `${this.fiatCode} dataset — check the acceptor's configuration card`
+          )
+        }
         this.rs232?.reject()
         return
       }
@@ -92,6 +110,13 @@ export class ApexValidator extends EventEmitter implements BillValidator {
     this.fsm.on('standby', () => this.emit('standby'))
     this.fsm.on('error', (err: Error) => this.emit('error', err))
 
+    if (!this.fiatCode) {
+      console.error(
+        '[APEX] starting with NO fiat code — denomination lookup will return null ' +
+          'for every credit channel and the acceptor will reject every note.'
+      )
+    }
+
     this.rs232.open((err) => {
       if (err) return cb(err)
       this.rs232!.reset() // start disabled
diff --git a/packages/hal/src/validators/ebds/index.ts b/packages/hal/src/validators/ebds/index.ts
index 44dd540..52a749b 100644
--- a/packages/hal/src/validators/ebds/index.ts
+++ b/packages/hal/src/validators/ebds/index.ts
@@ -53,6 +53,11 @@ export class EbdsValidator extends EventEmitter implements BillValidator {
   constructor(config: ValidatorConfig) {
     super()
     this.config = config
+    // Seed from config, as id003 effectively does by threading config.fiatCode
+    // into its rs232 config. Nothing in the app calls setFiatCode(), so a
+    // driver that relies on it alone resolves every credit channel to null and
+    // rejects every note. setFiatCode() stays available as a later override.
+    this.fiatCode = config.fiatCode ?? config.rs232.fiatCode ?? null
     this._throttledError = throttle((err: Error) => this.emit('error', err), 2000)
   }