Defining more than 4 TPDOs about canopen-stack HOT 2 CLOSED

I guess you try to use the TPDO COBID macro for getting the standard connection set CO_COBID_TPDO_DEFAULT(0 .. 3)?

This is no limitation of the CANopen stack, this is just a common recommended set of COBIDs from the CiA standard.

Background: the CANopen standard defines a so-called "standard connection set", which includes 4 TPDOs. This is ok when we assume a network with 128 nodes. This leads us to the needed range of COBIDs: 4 TPDOs x 128 Nodes = 512 COBIDs used for TPDOs. For smaller networks (for example only 16 nodes with NodeId 1..16), we can place more TPDOs within each node: 512 COBIDs / 16 Nodes = 32 TPDOs per node. The reason is the limited number of COBIDs in a CANopen network.

Proposal:
You can create an application-specific (or better: network-specific) connection set. With the _BASE and _INC values you can tweak the COBIDs for your specific use-case:

#define MY_COBID_TPDO_BASE    (uint32_t)0x180
#define MY_COBID_TPDO_INC     (uint32_t)0x8     /* 8 Nodes with NodeId 1..8 */
#define MY_COBID_TPDO_SET(num)  \
    CO_COBID_TPDO_STD(1u, MY_COBID_TPDO_BASE + (num * MY_COBID_TPDO_INC))

Alternatively, you can simply set an individual set of COBIDs directly:

#define MY_TPDO1_COBID()   CO_COBID_TPDO_STD(1u, 0x200)   /* 7 Nodes with NodeId 10h, 20h, 30h, .., 70h */
#define MY_TPDO2_COBID()   CO_COBID_TPDO_STD(1u, 0x201)
#define MY_TPDO3_COBID()   CO_COBID_TPDO_STD(1u, 0x202)
  :
#define MY_TPDO16_COBID()   CO_COBID_TPDO_STD(1u, 0x20F)

Any scheme is possible.

Whichever method you use, to get the CANopen network working, you must ensure that no COBID is used multiple times. So it depends on the number of nodes, possible node-IDs, number of TPDOs, and the COBIDs of all other services.

from canopen-stack.

Thanks; that makes a great deal of sense. My network is quite small, so I can easily adjust the TPDO COBIDs to accomplish this.

from canopen-stack.