14.2.7 FB/SFB 12 - BSEND - Sending data in blocksFB/SFB 12 BSEND sends data to a remote partner FB/SFB of the type BRCV (FB/SFB13). The data area to be transmitted is segmented. Each segment is sent individually tothe partner. The last segment is acknowledged by the partner as it is received, independ-ently of the calling up of the corresponding FB/SFB/FB BRCV. With this type of datatransfer, more data can be transported between the communications partners than is pos-sible with all other communication FBs/SFBs for configured S7 connections, namely65534 bytes.Please note that this block calls the FC or SFC 202 AG_BSEND inter-nally. These must not be overwritten! The direct call of an internal blockleads to errors in the corresponding instance DB!Depending upon communication function the following behavior is present:n Siemens S7-300 Communication (FB 12)– The send job is activated on a rising edge at REQ. The parameters R_ID, ID,SD_1 and LEN are transferred on each positive edge at REQ. After a job hasbeen completed, you can assign new values to the R_ID, ID, SD_1 and LENparameters. For the transmission of segmented data the block must be calledperiodically in the user program. The start address and the maximum length ofthe data to be sent are specified by SD_1. You can determine the job-specificlength of the data field with LEN.n Siemens S7-400 Communication (SFB 12)– The send job is activated after calling the block and when there is a rising edge atREQ. Sending the data from the user memory is carried out asynchronously tothe processing of the user program. The start address and the maximum length ofthe data to be sent are specified by SD_1. You can determine the job-specificlength of the data field with LEN. In this case, LEN replaces the length section ofSD_1.n If there is a rising edge at control input R, the current data transfer is cancelled.n Successful completion of the transfer is indicated by the status parameter DONEhaving the value 1.n A new send job cannot be processed until the previous send process has been com-pleted if the status parameter DONE or ERROR have the value 1.n Due to the asynchronous data transmission, a new transmission can only be initiatedif the previous data have been retrieved by the call of the partner FB/SFB. Until thedata are retrieved, the status value 7 will be given when the FB/SFB BSEND is called.The parameter R_ID must be identical at the two corresponding FBs/SFBs.ParametersParameter Declaration Data type Memory block DescriptionREQ INPUT BOOL I, Q, M, D, L Control parameter request, a rising edge activatesthe data exchange(with respect to the most recent FB/SFB call)R INPUT BOOL I, Q, M, D, L,constantcontrol parameter reset: terminates the active taskDescriptionFunctionVIPA SPEED7 Integrated StandardSystem Function Blocks > FB/SFB 12 - BSEND - Sending data in blocksHB00 | OPL_SP7 | Operation list | en | 18-30 737
