public:cbuspublic:start
Differences
This shows you the differences between two versions of the page.
Both sides previous revisionPrevious revisionNext revision | Previous revisionNext revisionBoth sides next revision | ||
public:cbuspublic:start [2020/01/22 15:24] – [Hardware requirements of the BUS] grovenor | public:cbuspublic:start [2020/01/22 15:57] – [CBUS - A universal layout control system] grovenor | ||
---|---|---|---|
Line 1: | Line 1: | ||
===== CBUS - A universal layout control system ===== | ===== CBUS - A universal layout control system ===== | ||
- | [[public: | + | |
- | [[public: | + | |
[[: | [[: | ||
==== Introduction ==== | ==== Introduction ==== | ||
- | CBUS is a Layout Control System | + | CBUS is a Layout Control System |
- | cbus.php and cbus2.php | + | * **[[https:// |
+ | * **[[https:// | ||
- | ==== The messaging scheme. ==== | + | A complete description |
- | After much debate, we settled on the ‘producer-consumer’ model at least for layout control. For those used to the idea of sending specific messages from A to B – a ‘source-destination’ scheme, this is a very different concept although widely used for industrial control systems. Imagine changing a switch on a control panel. This creates an ‘event’. A frame is sent on to the bus which contains no source address, no destination address, no information, | + | |
- | This is an extremely powerful and very flexible arrangement. Producers can send many events. Many consumers can act on an event and in different ways. Consumers can also act in the same way for different events. CBUS is a ‘one to many’ scheme which means that a specific event number will be restricted to one producer only. | + | |
- | The above description may seem rather abstract. Here is a recognisable example. You want a push button (PB) on a control panel to set a route and the corresponding signals. You have a producer node on the control panel. You have a number of consumer nodes that drive turnouts and signals. Let’s say the PB creates event number 1. Turnout controller A has been taught that event 1 means set turnout 1 to normal, turnout 2 to reverse. Turnout controller B has been taught that event 1 means set turnout 3 to reverse, turnout 4 to reverse and turnout 5 to normal. Signal drivers C and D have been taught that event 1 means set the various signals or aspects for that route. Pressing the one PB sets the route and all the signals in one go. Obviously, a different PB could send event 2. The various consumers would know to act on event 2 in a different way to event 1 so set a different route. | + | |
- | With this P-C model, you have effectively transferred some of the decision making from the producer to the consumer. It still allows for computer control or assistance, such as interlocking, | + | |
- | While full PC operation is easily accomplished, | + | |
- | As a result of experience with ' | ||
- | {{ http:// | + | ===== CBUS Documentation |
- | ===== CBUS in Brief ===== | + | This is the public view of CBUS and does not include MERG Technical Bulletins (TBs) or links to any other MERG Copyright material which is available only to members. |
- | This is a short overview, mostly useful to someone generally informed in the area, and wishing | + | |
- | CBUS is a local area bus designed | + | [[developerguide|CBUS Developers' |
+ | This Guide is intended | ||
+ | |||
+ | [[jmriacccmd|Commanding Accessory Decoders using CANCMD & JMRI]] | ||
- | A CBUS installation consists of a number of ' | ||
- | In situations where the Producer / Consumer model is inappropriate, | ||
- | ===== Identifiers ===== | ||
- | - **Nodes** are the basic unit of CBUS, and each is usually implemented on one PCB. Node-ids are 16-bit, and are assigned by the user. | ||
- | - **Event** messages are sent by ' | ||
- | * Short-event: | ||
- | * Long-event: 32-bit, made up of the concatenation of a node-id and a 16-bit event# | ||
- | * They are distinguished by the opcode of the message. | ||
- | ===== Message Formats ===== | ||
- | | ||
- | Where the opcode informs the receiving node what to do, using the data as necessary. | ||
- | There are many opcodes, including: | ||
- | - On-Events and Off-Events | ||
- | - Train control, including programming | ||
- | - Node configuration | ||
- | Long Event format is: { opcode, [node-id(2).event# | ||
- | Where the concatenation [node-id.event# | ||
- | Short Event format is: { opcode, node-id(2), device#(2) }, | ||
- | Where node-id and device# are independent. The device# is considered a ' | ||
- | More than one node can send this event, e.g. throttles, and it will have the same effect. | ||
- | By convention, device#s 1-9999 denote ' | ||
- | and device# 10000 the `Start-of-Day' | ||
- | | ||
- | The reason for this partition is that CABs can send short events up to 9999 and it would not be | ||
- | advisable for these to clash with sensor events by mistake. | ||
| | ||
===== Tools: ===== | ===== Tools: ===== | ||
Line 57: | Line 29: | ||
* **SSI** (Solid State Interlocker) from [[http:// | * **SSI** (Solid State Interlocker) from [[http:// | ||
- | ===== Implementation Notes ===== | ||
- | |||
- | * CBUS operates over CAN at 125kbps. | ||
- | * CAN is bidirectional and has built-in error correction and message re-send. | ||
- | * CBUS CAN frames have an 11-bit header and an 8-byte data-part. | ||
- | * The data-part carries the CBUS message. | ||
- | * The header must be unique, and this is ensured by including the 1 byte CAN-ID assigned to the sending node. | ||
- | * The CAN-ID is retained by the node, moving it to a new layout may cause a CAN-ID conflict. | ||
- | * In SLiM mode, the node-id is set by switches, and the CAN-ID is set equal to the low-byte of the node-id. | ||
- | * In FLiM mode, if the node does not have a CAN-ID, one is automatically obtained by self-enumeration: | ||
- | * NB: New modules //must// be introduced to the bus one at a time. | ||
- | * The CAN-ID may be re-assigned: | ||
- | * CBUS uses 29-bit header CAN messages for bootloading. | ||
- | * A complete description of CBUS including the full specification and implementation notes is contained in the ' | ||
- | | ||