How to run two trains automatically with a station passing loop

Step by step

1. 01

   Step 1: Understand the plan

   Only one train moves at a time. Each train has its own platform road (A or B) and stops at a sensor there. The rest of the circuit is treated as one block. A train must reserve the block before leaving and free it when it's back in its platform. EXRAIL's RESERVE(block) makes a train stop and wait if the block is already reserved, and FREE(block) releases it (DCC-EX EXRAIL reference).

   Next: step 2
2. 02

   Step 2: Fit the sensors

   Put a sensor near the far end of each platform road, leaving room for the train to stop. Wire them to two free pins – here 30 (road A) and 31 (road B). Test each one first.

   Next: step 3
3. 03

   Step 3: Make the points controllable

   Define your two points in myAutomation.h so EXRAIL can THROW and CLOSE them – for example SERVO_TURNOUT(id, pin, active_angle, inactive_angle, profile) for servos or PIN_TURNOUT for pin-driven motors (see the EXRAIL reference for DCC accessory points). Check which position (closed or thrown) leads into which road and swap the roads in the script if needed.

   Next: step 4
4. 04

   Step 4: Write the script

   Add this to myAutomation.h:

   ``` // myAutomation.h – two trains taking turns round one circuit // Turnout 1 = loop entry, turnout 2 = loop exit (define them first, // e.g. with SERVO_TURNOUT or PIN_TURNOUT) // Sensor 30 = stopping point in road A, sensor 31 = stopping point in road B // Block 1 = the single-track circuit outside the station

   SENDLOCO(3, 20) // loco 3 starts in road A SENDLOCO(4, 21) // loco 4 starts in road B DONE

   SEQUENCE(20) // the train that uses road A RESERVE(1) // wait here until the circuit is free CLOSE(1) CLOSE(2) // set both points for road A FWD(40) AFTER(30) // wait until we've cleared our own sensor AT(30) // ...and come back round to it STOP FREE(1) // let the other train go DELAY(20000) // 20 s in the platform FOLLOW(20)

   SEQUENCE(21) // the train that uses road B RESERVE(1) THROW(1) THROW(2) FWD(40) AFTER(31) AT(31) STOP FREE(1) DELAY(20000) FOLLOW(21) ```

   Each train first waits for block 1, sets both points for its own road, departs, waits until it has cleared its own sensor (AFTER), runs round until it reaches that sensor again (AT), stops, frees the block and waits in the platform.

   Next: step 5
5. 05

   Step 5: Upload and place the trains

   Upload with EX-Installer. Put loco 3 at the stopping point in road A and loco 4 in road B. Change the addresses in the SENDLOCO lines to suit your locos.

   Next: step 6
6. 06

   Step 6: Run it carefully

   Power up and watch the first few circuits with your finger near the power button. Adjust speeds and the platform DELAY.

   Next: step 7
7. 07

   Step 7: Build on it

   Once it's reliable you can add signals that change with the points (SIGNAL, RED, GREEN), random dwell times (DELAYRANDOM) or a third road.