Mumbai Monorail update: Tenders invited for Development and Refurbishment of Brake Translator Card for Monorail

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The Mumbai Metropolitan Region Development Authority (MMRDA) has invited sealed quotations from Manufacturer / Distributors Dealers / Other Firms on/before December 23rd, 2020 for Development and refurbishment of Brake Translator Card for Mumbai Monorail as per the requirement :

Sr. No Product Action Qty UoM Basic Rate (in INR) Total Amount (in INR) GST (in INR) Total Amount incl. GST(in INR) Expected delivery date
1. Brake Translator Card (Technical details and circuit diagram attached as per annexure l) Development & Refurbishment 04 Nos. Within l-2 weeks after receiving Purchase order
  Total Amount (INR)

All interested vendor must visit Mumbai Monorail Depot, Wadala for inspection of our faulty items and the quotation shall he submitted accordingly.

Overview of Brake Translator: 

The brake translator in the Mumbai Monorail is a bidirectional RS232 to RS485 converter. It acts as a translator for the signals from the driver control side (RS485) and the Brake Control Unit (BCU) (RS232),Information regarding the brakes (actuation,status,etc.) are worked through this translator. 

  • The existing brake translator card uses the ST232 and ST485 transceivers at both ends. 
  • The TTL signals from each of these ICs is worked to and from an ATmega168 microcontroller which presumably performs some error/packet checking from the proprietary software programmed into it. 
  • The microcontroller also toggles the status indication LEDs. 
  • The 24V supply given to this device is internally converted to a 5V/1A supply using the LM2675-5.0 fixed DC-DC converter. 
  • This 5V is used by all the other components, i.e. the ST232, ST485 and ATmega168. 


The Brake Translator modules were faulty, since swapping the Brake Translator modules would fix the non-communication issue between the driver control side and brake control unit (BCU). 

Scope of work: 

The scope of work for development and refurbishment of Brake Translator card is as given below: 

  • Examine all the parts and circuitry. 
  • Trace out the error. 
  • Replace the defective components.
  • Repair of 04 brake translator card. The repaired brake translator cards shall be put in the system and its functionality will be observed for a week. 

Source: MMRDA-Tender | Image Credit (representational): MMRDA

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