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Documentation Index

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Expansion module tools let you add serial, Ethernet, or wireless interfaces to routers that are already present in a live Packet Tracer topology — without tearing down and rebuilding the canvas. Packet Tracer requires a physical power cycle whenever a module is installed, so the bridge runtime patch handles it automatically: the device is powered off, the module is slotted in, and the device powers back on with skipBoot. Three tools cover module discovery and installation: pt_list_modules queries the built-in catalog, pt_add_module installs a single module with its own power cycle, and pt_install_modules_batch installs multiple modules across one or more routers in a single power cycle pass.

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pt_list_modules

Lists expansion modules available in the MCP-Packet-Tracer catalog. Without filters, all modules are returned. Use this tool to discover exact module names before calling pt_add_module or pt_install_modules_batch.

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Parameters

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router_model
string
Filter to modules compatible with a specific router model. Accepts the PT model identifier, e.g. "2911", "ISR4321", "2811". Modules that list no compatible_with constraint (generic modules) are always included. Omit to return all models.
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category
string
Filter by module category. Valid values:
  • router_hwic — HWIC cards for ISR G2 routers (1941, 2901, 2911)
  • router_nm — NM cards for older ISR G1 routers (2811, 2620XM, 2621XM, Router-PT)
  • router_nim — NIM cards for ISR 4000 series (ISR4321, ISR4331)
  • router_wic — legacy WIC cards

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Returns

A JSON object with count, the active filter, and a modules array. Each element contains:
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name
string
Exact module name to pass to pt_add_module, e.g. "HWIC-2T", "NIM-2T", "NM-4A/S".
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description
string
Human-readable description of what the module provides.
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category
string
Module category (router_hwic, router_nm, router_nim, router_wic, etc.).
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ports_added
array
List of port names that will appear on the device after installation, e.g. ["Serial0/0/0", "Serial0/0/1"].
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compatible_with
array | string
Array of compatible router PT model identifiers, or the string "any" if the module has no restriction.

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pt_add_module

Installs a single expansion module into a named slot on a device that already exists in the active Packet Tracer topology. The bridge runtime patch manages the power cycle automatically — you do not need to power off the device manually.

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Parameters

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device_name
string
required
The exact name of the device in the topology, e.g. "R1", "CORE-R2". Use pt_query_topology to list the names of devices currently in PT.
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slot
string
required
Slot identifier as a string. The format depends on the device type:
  • HWIC slots on 1941 / 2901 / 2911: "0/0", "0/1", "0/2", "0/3"
  • NM slots on Router-PT / 2811 / 2620XM / 2621XM: "1", "2"
  • NIM slots on ISR4321 / ISR4331: "0", "1"
  • Cloud-PT / hosts: "0", "1", … up to available slots
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module_name
string
required
Exact module name from the catalog, e.g. "HWIC-2T", "NIM-2T", "NM-4A/S", "HWIC-1GE-SFP". Use pt_list_modules to find valid names.
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dry_run
boolean
default:"false"
When true, validates the request and returns the JavaScript payload without sending it to PT. The bridge does not need to be connected for a dry run.

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Validation

Before the JS payload is sent, pt_add_module performs the following checks:
  • Module exists — module_name must match an entry in ALL_MODULES. An error is returned immediately if not found; use pt_list_modules to discover valid names.
  • Slot is a non-empty string — null, booleans, and empty strings are rejected.
  • Device exists in PT — a queryTopology() call confirms the device is in the active canvas (skipped when dry_run=true).
  • Module/router compatibility — if the module has a compatible_with list, the device’s reported model must appear in it (checked live against PT, skipped when dry_run=true).

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Return value

On success the response describes the installed module, the slot, and the ports added: 
Module installed in R1.
  Slot: 0/0
  Module: HWIC-2T — 2-port Serial WAN Interface Card
  Ports added: Serial0/0/0, Serial0/0/1
  PT powered the device off/on automatically.
On failure, PT’s rejection reason is reported along with common causes (occupied slot, incompatible model, wrong slot format).
Prefer pt_install_modules_batch when installing more than one module. Each pt_add_module call triggers a separate power cycle that can pause PT’s script engine for several seconds and risk timing out the bridge bootstrap poll loop.

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pt_install_modules_batch

Installs N modules across one or more devices in a single JavaScript runCode execution — one power-off sweep, all addModule calls, then one power-on sweep. This is the recommended tool when a topology requires serial links between multiple routers, because it avoids the per-call power-on delay that can cause the bridge bootstrap to time out.

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Parameters

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modules
array
required
A list of module installation descriptors. Each element is an object with:
  • device (string, required) — exact device name in PT
  • slot (string, required) — slot identifier (see slot addressing table below)
  • module (string, required) — exact module name from the catalog
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dry_run
boolean
default:"false"
When true, validates every entry against the catalog and returns the batch JS payload without sending anything to PT.

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Example

[
  { "device": "R1", "slot": "0/0", "module": "HWIC-2T" },
  { "device": "R1", "slot": "0/1", "module": "HWIC-2T" },
  { "device": "R2", "slot": "0/0", "module": "HWIC-2T" }
]
This installs four serial ports on R1 (Serial0/0/0, Serial0/0/1, Serial0/1/0, Serial0/1/1) and two on R2 (Serial0/0/0, Serial0/0/1) in a single power cycle.

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Validation

Each entry is validated individually against the catalog before the batch payload is built. Errors for any single entry abort the entire batch and return a detailed error list. Compatible-with checks are performed live against queryTopology().

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Return value

A JSON object with summary, total_modules, devices_affected, per-module status, and the js_payload. When dry_run=false and the bridge is connected, sent will be true and the summary confirms the batch was dispatched.

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Slot Addressing Reference

Router FamilySlot TypeValid Slot ValuesExample Module
1941 / 2901 / 2911HWIC"0/0" "0/1" "0/2" "0/3"HWIC-2T
ISR4321 / ISR4331NIM"0" "1"NIM-2T
Router-PT / 2811 / 2620XM / 2621XMNM"1" "2"NM-4A/S
Cloud-PT / hostsgeneric"0" … "7"PT-CLOUD-NM-1CGE
The slot parameter is always a string, not an integer. "0/0" and 0 address different slots on HWIC-capable routers. Passing a bare integer will be coerced to a string, but 0 becomes "0" which is a NIM-style slot — not the same as HWIC slot "0/0".

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Auto Serial Module Selection

The catalog includes a convenience mapping (SERIAL_MODULES) that recommends the correct serial module for each ISR router model. When building topologies programmatically, use this table to decide which module to pass:
Router ModelRecommended Serial ModulePorts Added
1941HWIC-2TSerial0/0/0, Serial0/0/1
2901HWIC-2TSerial0/0/0, Serial0/0/1
2911HWIC-2TSerial0/0/0, Serial0/0/1
ISR4321NIM-2TSerial0/1/0, Serial0/1/1
ISR4331NIM-2TSerial0/1/0, Serial0/1/1
The 2911 does not accept NM-4A/S. To add four serial ports to a 2911, install two HWIC-2T modules in slots "0/0" and "0/1" using pt_install_modules_batch.

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