DIN 14700: Truck-mounted fire-fighting equipment

The DIN 14700:2025 standard “Firefighting and fire protection - CAN interface for devices in emergency vehicles” is a German standard written in English language. It has been published in March 2025 and specifies CANopen-based interfaces for a body application unit (BAU) host controller and several dedicated fire-fighting units (FFUs). Such FFUs include warning signal units, water cannon units, powder extinguishing units, and light mast units. The standard provides parameter specifications and the related CANopen dictionary addresses as well as the mapping to PDOs (process data objects). Warnings and FFU diagnostic information are standardized, too. It is intended to submit the standard for international standardization to ISO or some other standardization body.

The ecosystem: DIN 14704 specifies the in-vehicle gateway unit (IGU)

The DIN 14700:2025 is part of a larger standardization approach as shown in Figure 1. Normally, the OEM-specific in-vehicle networks provide a gateway for body builders. In the past, this was often vehicle-specific. In the meantime, it is standardized in DIN 4630, which has been submitted to ISO and is currently in review under the name ISO 25200. DIN has specified an IGU (in-vehicle gateway unit) for fire-fighting vehicles based on DIN 4630 in the DIN 14704 standard (also written in English language). This document specifies parameters and mappings to J1939 parameter groups. The related interface to the fire-fighting host controller is not specified, but can be implemented by means of corresponding IGU parameter groups. But FMU (fleet management unit) and TGU (telematic gateway unit) parameters are not yet specified.

Figure 1: The DIN 14700 network is connected by means of the host controller to the ISO 25200 body builder network, which provides the in-vehicle network gateway unit to the truck networks (Source: CiA)

The fire-fighting host controller (HC) acts as a gateway between the J1939-based body application network and the CANopen-based network connecting the FFUs. It ensures that the FFUs have access to relevant vehicle-related information like engine speed and that data from the attached FFUs can be forwarded to other ECUs or human machine interface devices connected to the IVNs.

The DIN 14700 standard specifies the host controller (HC) and the FFU interfaces. In general, they comply with CiA 301 (EN 50325-4) CANopen application layer and communication profile. The following FFUs are standardized:

  • Battery charger unit (BCU) 1 to 5
  • Frequency inverter unit (FIU) 1 to 4
  • Light-mast unit (LMU) 1 to 2
  • Powder extinguishing unit (PEU)
  • Portable power generating unit (PGU)
  • Vehicle-mounted PGU
  • Portable water-pump unit (PWU) 1 to 3
  • Traffic warning unit (TWU)
  • Warning signal unit (WSU) 1 to 5
  • Water cannon unit (WCU) 1 to 3
  • Winding unit (WU)

The recommendations given in CiA 106, CiA 303-1, and CiA 301 specifications are suitable for DIN 14700 networks. The CANopen interface of fixed mounted FFU devices shall use 5-pin M12 plug circular connectors. The connector shall be A-coded and have in minimum IP67-rated protection.

The CANopen interface shall comply with the mandatory requirements of the CAN high-speed physical layer given in ISO 11898-2. Low-power and selective wake-up functionality should not be used. The transmission rate shall be 250 kbit/s. The bit-timing recommendations given in CiA 301 shall be applied, especially the sample-point range. Trunk and stub cables providing four wires for fixed-mounted devices and six wires for portable devices are recommended. The cables can be shielded. In case of using shielded cables, ground loops shall be avoided. The CAN interface shall not apply galvanic isolation between CAN protocol controller and CAN transceiver. The DIN 14700 devices shall not integrate termination resistors.

CANopen communication services

The CANopen FFU interfaces may support all communication services as specified in CiA 301. This includes SDO (service data object) access to all process data parameters also those mapped into PDOs as well as access to PDO communication and mapping parameters. DIN 14700:2025 is specified in a way that generic CANopen protocol stacks can be applied. The NMT (network management) manager functionality is implemented in the host controller. It consumes the heartbeat messages of all connected CANopen devices.

In addition to generic CANopen communication services, DIN 14700 standardizes a mandatory ERR (error) message. This is a dedicated PDO-like protocol and service. The periodically transmitted ERR message contains a 32-bit parameter with the latest warning or failure code. The complete list of legacy warning and failure codes can be accessed by means of SDO services.

Process data parameters: Mapped into pre-defined PDOs

DIN 14700 specifies PDO messages, which have a pre-defined length of 8 byte (data field). The standard specifies all transmit PDOs (TPDOs) regarding communication parameters and mapping parameters as well as the corresponding receive PDOs (RPDOs). In order to achieve a high degree of interoperability, PDO parameters are not configurable.

TPDOs are sent by the CANopen device, when it transits from the NMT pre-operational state to the NMT operational state. They are transmitted periodically. RPDOs are processed after reception within the TPDO event time.

The pre-specified PDO connection set as given in CiA 301 does not apply to this document. This means, the used CAN-IDs (identifiers) of the PDO messages are specified by DIN 14700. Therefore, generic devices need to be configured regarding the used CAN-IDs for PDOs, in order to avoid double use of CAN-IDs in the same network segment.

Figure 2: A PDO is produced by the host controller and consumed by the WSU and LMU 1 as well as LMU 2 (Source: CiA)

In some cases, a TPDO of the host controller can be relevant for different FFUs (see Figure 2). The corresponding FFUs listen to such PDO messages simultaneously. On the CAN data link layer, the related data frames are distributed in broadcast. Every CAN node is able to read every CAN data frame. The CANopen protocol stack decides on basis of the implemented PDO communication parameter, if a PDO is processed or not.

The parameters mapped into PDOs are also specified in DIN 14700. They have unique addresses in the CANopen object dictionary, which allows SDO read and write accesses for diagnostic and troubleshoot purposes. Having SDO access to the parameters enables the use of generic and dedicated tools available from different suppliers.

Future of DIN 14700

DIN has submitted the DIN 14700 standard to ISO (TC 22/SC 31) for international standardization. It is intended to add new features. One of them is the connection to the cloud by means of a telematic gateway unit (TGU). Further feature requests are in the pipeline and will be discussed when DIN 14700 becomes an ISO standard.