9Control Unit (CU) requirements#

9.1General#

The control system requirements defined in MRTS201 General Equipment Requirements apply to this Technical Specification. Vehicles used for mounting TVMS shall comply with the control requirements of the host vehicle specified in the Queensland MUTCD Part 3 and this Technical Specification in order of preference. Additional control system requirements for equipment provided under this Technical Specification are described below.

Each TVMS shall be controlled by a CU that is operated in the following order of priority:

  1. 1.local facility switch
  2. 2.hardwired input(s)
  3. 3.maintenance communications port, and
  4. 4.control communications ports.

Software shall be provided in accordance with Clause 10. The DU shall be able to be controlled individually or simultaneously. The CU of each TVMS shall:

  1. a)conduct all processing associated with the communications support for paired signs
  2. b)ensure that the requested messages are immediately displayed on the TVMS sign LED display and carries out all associated processing and monitoring functions
  3. c)monitor, log and report the operation of each connected sign display individually
  4. d)monitor, log and report events crucial for the operation of the sign
  5. e)allow the TVMS to be controlled individually or as part of a pair
  6. f)be capable of storing all recommended message frames in its non-volatile memory, refer to QGTM Part 10 for the recommended messages
  7. g)command signs to display only the allowable messages for that respective site as defined by QGTM Part 10
  8. h)allow local automatic reset of sign displays and the CU itself, such as via watchdog(s)
  9. i)be capable of automatically dimming connected signs based on the average of the light sensor outputs (automatic dimming of the sign occurs to increase ambiance, automatic dimming is not permitted for the sole purpose of extending the battery life)
  10. j)accept / reject valid or invalid commands made by the SRD, RSCS, configuration software
  11. k)allow a unique electronic identification for each site to be configured
  12. l)electronically verify with the connected sign display that the displayed message is consistent with the message originally requested and permitted
  13. m)accept an analogue input from a Local Facility Switch (LFS), and
  14. n)additional information and functionality of the CU required is described in the following sections.

9.2Permissible message types#

Each TVMS CU shall be configured to store only those message types permitted to be displayed as defined in QGTM Part 10 for the site in which they are operating. This will be achieved through the RSCS or configuration software referred to in this Technical Specification. The CU shall ensure that only messages permitted for that site are displayed on its respective signs.

The CU shall allow:

  • a) the configuration software to read and write its permitted messages / message combinations
  • b) the RSCS to read its stored messages, and
  • c) stored messages to be downloaded to the sign(s) only when required to be displayed.

The permissible messages for each site shall be confirmed with the Principal.

9.3Message display time#

The minimum display duration of each message frame shall be configurable and accessible via the TVMS configuration software. The time range and factory default settings are shown in Appendix A.

9.4Watchdog#

The TVMS display and CU must each monitor the state of its respective processor and blank the respective display(s) if processor failure occurs.

The CU shall generate an alarm and blank all signs if the integrity of the firmware or configuration is compromised.

9.5Global Positioning System (GPS)#

Each TVMS sign shall be fitted with a GPS receiver. The onboard GPS receiver shall monitor the location in 3 dimensions (latitude, longitude and altitude) of each sign and also synchronise the TVMS CU internal clock. The CU shall provide an alarm if a sign is moved beyond a 30 m radius of its installed position. This may be achieved using a virtual perimeter or 'geo-fence'.

Vehicles that mount TVMS, and which are compliant with the Queensland MUTCD Part 3, may not require GPS.

9.6Directional compass capability#

Each TVMS may have the ability to discern the installed directional orientation and whether any subsequent change in direction has been detected through the use of a magnetometer or inertial type sensor.

9.7Handheld short-range device (SRD)#

The local method of control is via a hand-held SRD communications device. The following requirements shall apply to the use of the SRD:

  • a) have a unique ID (refer to Clause 8.5 above) that is transmitted with each message change request
  • b) should a RSCS message change request occur at the same time as the message change request from an SRD, the SRD request shall have priority and the RSCS request shall be ignored
  • c) for wireless SRD, use 'code hopping' or 'rolling code' technology, to prevent unauthorised use of the signs through 'replay attacks'
  • d) for wired SRD, the leads shall preferably be securely terminated in the RS-232 / Ethernet port of the TVMS sign or any other secure termination resulting in 15 m lead
  • e) the CU shall have the ability to deactivate an SRD from controlling the TVMS sign (for example, due to lost or damaged SRDs) through the TVMS configuration or RSCS software, and
  • f) only when an SRD message activation button is pressed and held for 2 seconds shall a control message be transmitted.

To guard against accidental activation of a TVMS frame from the SRD, buttons must be pressed and held for 2 seconds before any TVMS message frame will be changed.

9.8Local Facility Switch (LFS)#

A 5-position key operated facility switch that complies with MRTS201 General Equipment Requirements shall be provided to enable selection of the following 5 display functions for each of the text display and the graphics display:

  1. 1.Blank / Maintenance
  2. 2.NORMAL, or
  3. 3.3 message modes.

9.8.1Blank / maintenance mode#

Where Blank / Maintenance mode is selected on an LFS, the following requirement shall apply:

  • a) the hardwired sign display of that TVMS sign shall be blanked
  • b) whilst this mode is selected at the particular TVMS sign, any subsequent display requests from a RSCS software session or SRD shall be ignored
  • c) the TVMS sign shall remain powered
  • d) where 2 signs have been configured as one pair, selecting the LFS to 'BLANK' on one TVMS sign shall not blank the other paired TVMS sign unit
  • e) a locally connected PC / laptop running the configuration software shall be permitted to perform all status, maintenance and diagnostic functions on the respective TVMS sign, and
  • f) the LFS shall be designed as fail-safe operation and, as such, should it fail or be disconnected, Blank / Maintenance mode will be activated.

The purpose of an LFS is to provide manual local override and blank the sign display or perform local maintenance and diagnostic functions, if required.

9.8.2NORMAL mode#

Where NORMAL mode is selected on the LFS, the displayed message is selected via the maintenance communications port and/or the control communications port. The followings shall apply:

  • a) the hardwired sign display of that TVMS is active
  • b) the CU shall accept remote control communications from a remotely connected PC / laptop running the RSCS software, and
  • c) the CU shall accept remote control communications from a designated local handheld SRD.

9.8.33 message modes#

3 modes labelled Message 1, Message 2, and Message 3 display either Message 1, 2 or 3. The messages shall be in accordance with QGTM Part 10.

Control via all communications ports inhibited; status and diagnostic commands via all communications ports remain functional.

9.9Hardwired inputs#

Where required, the TVMS controller shall have the ability to display a predefined message when it receives a voltage free contact closure or similar input from an external device such as a loop detector or vehicle over-height detector.

Unless otherwise specified, the TVMS controller shall be capable of accepting a minimum of 6 hardwired inputs.

9.10Communication protocol#

Where connection to STREAMS is required, the communication between the Field Processor and the TVMS CU shall comply with TSI-SP-003, MRTS232 Provision of Field Processors and MRTS201 General Equipment Requirements.

9.11Bus arbitration#

Each TVMS shall act as a slave on the EIA RS-422A / modem bus.

9.12Message hierarchy#

Each TVMS controller shall provide a user-configurable message hierarchy for message selection commands and hardwired inputs.

9.13Sign monitoring and logs#

The CU shall monitor and log the following items, which shall be configurable to raise an alarm:

  • a) any SRD message requests of the CU, including the unique identifier of the SRD requesting message change
  • b) all RSCS software requests of the CU, including the RSCS username under which the request was made
  • c) all unauthorised RSCS software requests of the CU, including the RSCS username under which the request was made
  • d) loss of communications with the sign (noting the type of communication for example, SRD, RSCS, and so on)
  • e) high internal sign enclosure temperature
  • f) movement of the sign from its installed position
  • g) LED faults
  • h) initialisation of TVMS (power up)
  • i) when an SMS critical alert request has been transmitted by the CU
  • j) changed state of LFS (that is, NORMAL or Blank / Maintenance)
  • k) low battery voltage (for example, where the voltage of the power supply battery drops to a level that would prevent the battery from being recharged by the charging system)
  • l) loss of solar charge current / voltage
  • m) loss of load current
  • n) internal component faults (GPS and other modular hardware components), and
  • o) all configuration changes (for example, made through configuration or RSCS software).

The log shall identify the sign (through its respective sign ID) and its fault. The log shall include the date and time stamp for all entries and may be exported in a readily acceptable format, such as comma delimited text file (.csv), Microsoft Excel (.xls) or other formats as agreed with the project representative.

The log shall also report when the fault condition has cleared and subsequently returns to normal operation.

The log file storage for the event log shall be sufficient to allow at least 8 days of continuous logging without overwriting. The oldest event record shall be overwritten first when the log file storage capacity has been exceeded.

For critical faults defined in Clause 9.14 below, the log shall include the RSCS or configuration software username ID which performed the acknowledgement and clearing of the fault.

Where a RSCS connection is in session, the RSCS software shall be synchronised and receive updates dynamically from the respective CU.

9.13.1Turning motion sensor#

Each TVMS may have the ability to detect whether the unit’s position has been altered from the installed position through the use of gyroscope.

The GPS receiver, directional compass and gyroscope facility will allow greater visibility of how the site layout is set out and whether any subsequent changes have occurred due to any number of scenarios.

9.13.2Power system monitoring#

The power system log is used for discerning the proper operation of the power system. The CU shall log the electrical parameters (referred to in Clause 9.15) for each connected sign within the roadwork site. For solar charge current / voltage, load current and battery charge voltage, the CU will aggregate the measurements that it receives from the connected signs over a one hour period using rolling averages.

Each sign shall report no less than 4 measurements for each parameter per hour to the connected CU.

9.13.3LED intensity control#

The LED intensity shall be controlled to provide constant apparent brightness, and maximum legibility distance, for the complete range of ambient light under which the TVMS shall operate. Each TVMS shall support automatic brightness variation, where the TVMS determines the LED brightness level using a light sensor reading and a predefined set of light sensor values. Each TVMS shall be provided with at least 2 light sensors to detect ambient light levels. These sensors shall be located as follows:

  • a) one sensor facing forward perpendicular to the sign face, and
  • b) one sensor facing backward perpendicular to the sign face.

9.13.4Temperature control#

Each TVMS shall be provided with at least one temperature sensor to measure the temperature inside the display enclosure near the top centre. The sensor shall not be mounted directly against the top face of the display enclosure. The temperature reading shall be available through the use of a protocol message via STREAMS. The temperature shall be presented in Centigrade units.

9.14Critical faults#

Critical faults shall also include the following:

  • a) movement of the sign after installation – this is required to ensure the sign location has not been altered after installation due to unauthorised tampering, vehicular incident, wind and other reasons (a number of sensors will be used to determine whether the sign has been moved)
  • b) LED pixel faults – for example, which cause the display to be blanked (see Clause 11.2)
  • c) low battery voltage level alarm – when the battery level falls to the specified DoD (for example, indicating insufficient charge or problem with charging circuit)
  • d) charging voltage too high – when the battery charge voltage exceeds the maximum charge voltage for the selected battery (for example, indicating a possible battery charger regulator problem)
  • e) loss of solar module – for example, open circuit detected on solar power charging circuit, and
  • f) loss of load – for example, possible disconnection of extension cable between trailer / concrete block and sign display.

9.15Alarms#

Each sign shall be fitted with an SMS mobile phone alert system (refer to Clause 8.2.2). Where critical faults occur:

  • a) an SMS notification will be sent from the respective CU to pre-specified phone numbers with a clear description of the site ID and a description of the fault
  • b) if the sign is connected to the RSCS, an alarm shall also be generated on the user alarm monitoring interface, and
  • c) the respective TVMS sign display shall be blanked only.
Source: MRTS262 · pages 16–23 Open PDF at this page Search this document