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CTC panels for use with APB/CTC signal system

Definitely moving forward!!

The concept is as follows:
We have a generic PCB with controller, output shift registers (74595), and input lines for buttons, as well as MRBus communication circuitry. These PCBs are approximately 100 x 160 mm x mm in size, and mounted into aluminum boxes 56 mm high. These boxes have got two sub-d 9 pin connectors on either end, male on the right side and female on the left, so that they can be daisy-chained. The connectors provide power and MRBus to the single modules; additionally, the pin layout includes TX and RX pairs, so that the controllers can selectively communicate with their adjacent partner, allowing for the generation of geographic module sequence information.

Prototype of panels (here, buttons and layout are completely different for a completely different application)

Basically, the panels contain information where the status byte of a certain APB can be found in the data stream. That information includes the three known elements "packet source", or what node the packet comes from, "packet type", standardized as 'S' (0x53) for safety-relevant packets, and "byte", indicating the byte number in the packet. This information is sent to the neighboring/adjacent panel module, which safes it and, in turn, sends it to its field device via "write EEPROM ('W')" data packets. This process is controlled, reaching the "completed" status only if all write commands have been acknowledged by the field device.

This programming mode is reached by pressing the "Program" button on the panel module. A long press flushes the geographic information and allows reconfiguration of all APB interfaces, whereas a short press only modifies a single interface. In order not to unintentionally enter the "program" mode during normal operation, the Shift button has to be pressed simultaneously.

When in Programming mode, a short press onto an APB interface/signal button enables programming of it: the controller starts sending its data, and enables the receiver on the associated RX line (on the sub-d connectors). When the same is done on the neighboring module, the two exchange information and, if valid, close this step on the respective APB interface. This is shown by the yellow lamp lighting up. When all APB interfaces have been configured (all lamps yellow), data is sent to the field devices. When reception is confirmed for all three bytes, the respective lamp goes to green, indicating completion. Again, if all APB interfaces have been programmed into the field devices' EEPROM, the program status lamp goes to green for a short time, and the panel module switches to normal operation mode.
When in Programming mode, a long press on an APB interface's/signal's button configures this interface to INTERFACE_DISABLED, by programming the values 0x00 for packet source, 0x00 for packet type, and 0 for byte number. This effectively disables reception of status information for this interface.

Documentation and Source Code

Schematics