SAP5SD-A-G1-R datasheet(34/67 Pages) RENESAS

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SAP51 / SAP5S Datasheet

January 28, 2016

5.8.3.

Synchronous Data I/O Mode

Since the slaves in an AS-i network are called successively by the master, the data input and output operations of

different slaves are not normally synchronized. If there is, however, an application that requires accurate

synchronized data I/O timing, the respective slaves can be operated in the Synchronous Data I/O Mode. With

respect to communication with the master, slaves running in the Synchronous Data I/O Mode behave like regular

slaves. However, the input data sampling as well as the output data driving is determined by the polling cycle of

the respective AS-i network as described below.

Activation of the SAP5 Synchronous Data I/O Mode is related to the EEPROM flags Synchronous_Data_IO and

P2_Sync_Activation (refer to Table 4.2) and the value of the Parameter Port P2 Output Register as follows:

NOTE: The input signal at Parameter Port P2 does not affect activation of Synchronous Data I/O Mode. Only the

master can change the activation status by sending a corresponding Write_Parameter (WPAR) request.

Table 5.12 Activation of the Synchronous Data I/O Mode

Synchronous_Data_IO

P2_Sync_Activation

Parameter P2 Output Register

Synchronous Data I/O Mode

OFF

NOTE: The Synchronous Data I/O Mode is not available if the Safety Mode is enabled.

If Synchronous Data I/O Mode is activated, input data sampling as well as the output data driving events are

moved to different times synchronized to the polling cycle of the AS-i network. Nevertheless, the communication

principles between master and slave remain unchanged compared to regular operation. The following rules apply:

• Data I/O is triggered by the DEXG call to the slave with the lowest slave address in the network. Based on

the fact that a master is calling slaves successively with rising slave addresses, the SAP5 considers the

trigger condition true if the slave address of a received DEXG call is less than the slave address of the

previous correctly received DEXG call.

• Data I/O is only triggered if the slave has correctly received data during the last cycle. If the slave did not

receive data (i.e., due to a communication error), the Data Outputs are not changed and no Data Strobe is

generated (the “arm+fire” principle). The inputs however, are always sampled at the trigger event.

• If the slave with the lowest address in the network is operated in the Synchronous Data I/O Mode, it

postpones the output event for the received data for a full AS-i cycle. This is to keep all output data of a

particular cycle image together.

Note: To make this feature useful, the master must generate a data output cycle image once before the

start of every AS-i cycle. The image is derived from the input data of the previous cycle(s) and other control

events. Once an AS-i cycle has started, the image must not change. If A and B slaves are installed in

parallel at one address, the master must address all A-Slaves in one cycle and all B-Slaves in the other

cycle.

SAP5SD-A-G1-R Datenblatt(PDF) 34 Page - Renesas Technology Corp