TRM-915-R250 datasheet(11/39 Pages) LINX

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User Networking Mode

User Networking Mode is a more complicated scheme than GUID

mode. It uses the customer ID bytes (regCUSTID[0-1]) and two of the

user destination bytes (regUSERDESTID[0-1]) as a destination address.

The customer ID bytes are programmed at the factory and cannot be

changed. The module’s local address is contained in two of the user

source ID registers (regUSERSRCID[0-1]). Each module also has a user ID

mask (regUSERIDMASK[0-1]) that provides an additional logical layer of

addressing and can be used to create sub-networks. The receiving module

masks its local address and the received destination address by calculating

the logical AND with the user ID mask. If the results are equal, then the

payload is output on the UART. The customer ID bytes are not masked, but

must match the local value.

If acknowledgements are enabled, only the module with a user source ID

that matches the transmitted user destination ID responds. The mask is not

used for this determination.

If the result of the user ID Mask AND the received user destination address

equals the same value as the user ID mask, then the payload data is output

on the UART. This acts as a broadcast message to the network.

Setting the mask to 0xFFFF removes the mask and only the source and

destination addresses are used for networking. When using user network

mode to send packets to multiple users and the mask is not equal to

0xFFFF, acknowledgements must be disabled. Failure to do so could cause

extreme delays in transmission and loss of data.

As an example, if the mask is 0xFFF0 and the destination address

transmitted by the sender is 1234, then all modules with a source ID of

123x respond. This gives a subnet of 16 modules (where x = 0 to F) and

acts as a broadcast message to the sub-net. Acknowledgements should

be disabled.

Figure 14 shows this example and Figure 12 and Figure 13 show some

more examples of user networking mode.

Figure 12: 250 Series Transceiver User Network Mode Examples

250 Series Transceiver User Network Mode Examples

Destination

ID from

Received

Packet

Receiver

Source

Receiver

User ID

Mask

Result of

Dest

AND

Mask

Result of

Source

AND

Mask

Action

3000

2000

E000

2000

The results are equal, so

the payload is output on

the UART.

3000

2000

The results are equal, so

the payload is output on

the UART. The destination

ID and the source ID

match, so an ACK is

transmitted if enabled.

4000

The results do not match,

so the packet is discarded.

3000

2000

F000

3000

2000

The results do not match,

so the packet is discarded.

3000

The results are equal, so

the payload is output on

the UART. The destination

ID and the source ID

match, so an ACK is

transmitted if enabled.

4000

The results do not match,

so the packet is discarded.

E000

2000

E000

2000

The destination ID matches

the user ID mask, so the

data is output on the UART.

3000

2000

4000

250 Series Transceiver User Network Mode Examples

Sender

Receiver

Network

Mode

User

SRCID

User

DESTID

User

SRCID

User

IDMASK Response

0x06

(User)

0x1000

0xFFFF

0x2000

0XFFFF

Data output by both modules. No

ACK sent by either module.

0x3000

0xFFFF

0x16

(User +

ACK)

0x1000

0xFFFF

0x2000

0xFFFF

Data output by both modules. No

ACK sent by either module. This

configuration causes transmission

problems.

0x3000

0xFFFF

0x16

(User +

ACK)

0x1000

0x3000

0x2000

0xE000

Data output. No ACK sent.

0x3000

0xE000

Data output. ACK sent to

0x1000.

0x6

(User)

0x1000

0x3000

0x2000

0xF000

Not processed – discarded.

0x3000

0xF000

Data output. No ACK sent.

Figure 13: 250 Series Transceiver User Network Mode Examples

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