Auto: ablegacy-13 — DH+ via 1756-DHRIO bridging validation

Closes #256

scripts/e2e/test-ablegacy.ps1

@@ -54,6 +54,16 @@
   Failure threshold the server is configured with (default 3). The
   demote assertion writes/reads N+1 times against the killed simulator
   to guarantee the threshold trips even if some reads beat the kill.
+
+.PARAMETER DhPlusStation
+  PR ablegacy-13 / #256 — DH+ node address (octal 0..77 == decimal 0..63)
+  of a PLC-5 reachable through a 1756-DHRIO module. **Documentation
+  parameter only — there is no automated assertion**: libplctag's ab_server
+  does not simulate the DHRIO + DH+ + PLC-5 stack, so wire-level coverage
+  requires real hardware. When supplied alongside a `-Gateway` of the form
+  `ab://<host>/1,<slot>,2,<station-octal>` and `-PlcType Plc5`, the value
+  here is recorded in the run log so reproducibility is auditable. See
+  docs/drivers/AbLegacy-DH-Bridging.md for the manual smoke procedure.
 #>
 
 param(
@@ -64,7 +74,11 @@ param(
     [Parameter(Mandatory)] [string]$BridgeNodeId,
     [string]$DiagnosticsRequestCountNodeId,
     [string]$DiagnosticsDemoteCountNodeId,
-    [int]$FailureThresholdForDemote = 3
+    [int]$FailureThresholdForDemote = 3,
+    # PR ablegacy-13 / #256 — DH+ station via 1756-DHRIO bridging. Doc-only:
+    # no automated assertion (no Docker fixture covers DH+). See script header
+    # comment + docs/drivers/AbLegacy-DH-Bridging.md.
+    [string]$DhPlusStation
 )
 
 $ErrorActionPreference = "Stop"