8.2.9 FB/SFB 12 - BSEND - Sending data in blocks
FB/SFB 12 BSEND sends data to a remote partner FB/SFB of the type BRCV (FB/SFB
13). The data area to be transmitted is segmented. Each segment is sent individually to
the 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 data
transfer, more data can be transported between the communications partners than is pos-
sible with all other communication FBs/SFBs for configured S7 connections, namely
65534 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 block
leads 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 has
been completed, you can assign new values to the R_ID, ID, SD_1 and LEN
parameters. For the transmission of segmented data the block must be called
periodically in the user program. The start address and the maximum length of
the data to be sent are specified by SD_1. You can determine the job-specific
length 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 at
REQ. Sending the data from the user memory is carried out asynchronously to
the processing of the user program. The start address and the maximum length of
the data to be sent are specified by SD_1. You can determine the job-specific
length of the data field with LEN. In this case, LEN replaces the length section of
SD_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 DONE
having 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 initiated
if the previous data have been retrieved by the call of the partner FB/SFB. Until the
data 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.
Parameters
Parameter Declaration Data type Memory block Description
REQ INPUT BOOL I, Q, M, D, L Control parameter request, a rising edge activates
the data exchange
(with respect to the most recent FB/SFB call)
R INPUT BOOL I, Q, M, D, L,
constant
control parameter reset: terminates the active task
Description
Function
VIPA SPEED7
Network Communication
Ethernet Communication > FB/SFB 12 - BSEND - Sending data in blocks
HB00 | OPL_SP7 | Operation list | en | 18-30 158
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