Safety Process Data Object (SPDO)

7.7 State and sequence diagrams

7.7.1 Safety Process Data Object (SPDO)

7.7.1.1 Safety Process Data Object producer (TxSPDO)

The producer shall start sending its data cyclically or on state changes when switching to Operational.

NOTE The refresh time for sending the data can be adjusted within the SOD.

The Safety Process Data Object Producer state diagram is specified by Figure 43.

Tx

IDLE (Δt expired)

OR ((data(new) exists) AND (CT increased))

data sent Tx

IDLE (Δt expired)

OR ((data(new) exists) AND (CT increased))

data sent

Figure 43 – State diagram TxSPDO

The Safety Process Data Object Producer sequence diagram is specified by Figure 44.

Key

See Table 171.

Figure 44 – SPDO communication producer Table 171 specifies items used in Figure 44.

Table 171 – SPDO communication producer item description

Item Description Min value Max value SOD data_new New data from

safety related application or new TRes received

- - -

t Internal time [CT] 0 65 535 - Δt Refresh prescale

[CT]

1 32 767 Object Index 1C00h -- 1FFEh sub index 02h (see 7.5.4.16)

Δt1 Time difference of new data [CT]

>0 Δt -

Table 172 specifies the SPDO communication producer states.

Table 172 – SPDO communication producer state description

State Description

Tx Sending data

IDLE Wait until refresh time elapsed or new data available

7.7.1.2 Safety Process Data Object consumer (RxSPDO) 7.7.1.2.1 General behaviour

For each received RxSPDO action as specified in the Safety Process Data Object Producer, state diagram (Figure 45) shall be taken by the consumer. The data shall be processed.

Processing data shall include time synchronization and time validation, see 7.7.1.2.2. If a consumer receives valid data from a producer, the SCT timer shall be restarted. If the SCT timer elapses, all data related to the RxSPDO shall be set to a safe state.

Producer

data & t

data & (t+Δt) data_new & (t+Δt+Δt1) Δt

Event Non safe communi- cation layer

data new

data & t

data & (t+Δt)

data_new & (t+Δt+Δt1)

Figure 45 – State diagram RxSPDO

The Safety Process Data Object Consumer sequence diagram is specified by Figure 46.

Key

See Table 173.

Figure 46 – SPDO communication consumer Table 173 specifies the item used in Figure 46.

Table 173 – SPDO communication consumer item description

Item Description Min value Max value SOD

SCT Safety control time [CT] 1 UNSIGNED32 Object 1400h -- 17FEh sub index 02h (see 7.5.4.14) IDLE

Process data

data received

SCT elapsed

Set RxSPDO data to safe

state Write

diagnose data to SOD

Start SCT Data

invalid

Data valid data received Time synchronization

failure

Consumer data1 & t1

data1 & t1 data1 & t2 data2 & t2 data2(corrupted) & t2 data2(corrupted) & t3 data2(corrupted) & t3 data2(corrupted) & t3

data2 & t3 Non safe communi-

cation layer data1 & t1

data1 & t2 data2 & t2 data2 & t3

new data, new time, process old data, old time, ignore old data, new time, process new data, old time, ignore

data corrupted, ignore data corrupted, ignore SCT elapsed,

set RxSPDO data to safe state,

new data, new time, process data

Table 174 specifies the SPDO communication consumer states.

Table 174 – SPDO communication consumer state description

State Description

IDLE Waiting for data

Process data Performing timing validation and time synchronization.

Process data according to SPDO mapping

Start SCT Reset the SCT

Write diagnose data to SOD The diagnose data has to be available for the user.

This is made through the SOD

Set RxSPDO data to safe state All data related to the producer will be set to zero

7.7.1.2.2 Process data

The process data state diagram is specified by Figure 47.

Key

See Table 175 and Table 176.

Figure 47 – State diagram process data Table 175 specifies items used in Figure 47.

Validate timestamp

Validate RxSPDO frame

CT has changed and increased

CT has not changed or decreased / data is invalid

Data with TRes received

Process TRes

Check propagation

delay deviation

Map data Data is valid [propagation delay deviation is ok] / store CT

Data is invalid [propagation delay is too long]

Data without TRes

Time

synchronization failure [propagation delay is too short]

Table 175 – SPDO communication consumer telegram validation item description

Item Description Min value Max value SOD

CT Consecutive Time field 0 65 535 -

TRes Time synchronization response, consists of TR (Time Request Distinctive Number Field) and TADR (Time Request Address) within the safety PDU

- - -

Table 176 specifies the process data states.

Table 176 – SPDO communication consumer telegram validation state description

State Description Validate timestamp If the timestamp (CT) is equal to or less than the timestamp of the

previously valid telegram, the telegram shall be ignored

Validate RxSPDO PDU frame Checks if the PDU contains time synchronization data for this node Process TRes See 7.7.2.7

Check propagation delay deviation Checks timestamp validity

Map data Writes the data into the SOD according to the RxSPDO mapping