diff --git a/src/std/rec/seqRecord.dbd.pod b/src/std/rec/seqRecord.dbd.pod index 826f3ecf6..077d36107 100644 --- a/src/std/rec/seqRecord.dbd.pod +++ b/src/std/rec/seqRecord.dbd.pod @@ -6,12 +6,294 @@ # EPICS BASE is distributed subject to a Software License Agreement found # in file LICENSE that is included with this distribution. #************************************************************************* + +=title Sequence Record (seq) + +The Sequence record is used to trigger the processing of up to ten other records +and send values to those records. It is similar to the fanout record, except +that it will fetch an input value and write an output value instead of simply +processing a collection of forward links. It can also specify one of several +selection algorithms that determine which values to write. It has no associated +device support. + +=recordtype seq + +=cut + menu(seqSELM) { choice(seqSELM_All,"All") choice(seqSELM_Specified,"Specified") choice(seqSELM_Mask,"Mask") } + recordtype(seq) { + +=pod + +=head1 Contents + +=over + +=item * L + +=over + +=item * L + +=item * L + +=item * L + +=item * L + +=item * L + +=item * L + +=item * L + +=back + +=item * L + +=back + +=begin html + +

+ +=end html + +=head2 Parameter Fields + +The fields fall into the following categories: + +=over + +=item * L + +=item * L + +=item * L + +=item * L + +=item * L + +=item * L + +=item * L + +=back + +=head3 Scan Parameters + +The sequence record has the standard fields for specifying under what +circumstances it will be processed. These fields are listed in L. +In addition, L explains how these fields are used. + +=head3 Desired Output Parameters + +These fields determine where the record retrieves the values it is to write to +other records. All of these values are not necessarily used, depending on the +selection algorithm. + +The sequence record can retrieve up to 16 values from 16 locations. The user +specifies the locations in the Desired Output Link fields (DOL0-DOLF), which can +be either constants, database links, or channel access links. If a Desired +Output Link is a constant, the corresponding value field for that link is +initialized to the constant value and ''cannot'' be changed via dbputs. +Otherwise, if the Desired Output Link is a database or channel access link, a +value is fetched from the link each time the record is processed (provided that +the output link is part of the record's selection algorithm). See L
for information on how to specify database links. + +The value fetched from the Desired Output Links are stored in the corresponding +Desired Output Value fields (DO0-DOF). These fields can be initialized to a +constant value, but they cannot be changed via dbPuts. + +=head4 Desired Output Link Fields + +=fields DOL0, DOL1, DOL2, DOL3, DOL4, DOL5, DOL6, DOL7, DOL8, DOL9, DOLA, DOLB, DOLC, DOLD, DOLE, DOLF + +=head4 Desired Output Value Fields + +=fields DO0, DO1, DO2, DO3, DO4, DO5, DO6, DO7, DO8, DO9, DOA, DOB, DOC, DOD, DOE, DOF + +=head3 Output Parameters + +When the record is processed, the desired output values are retrieved for the +links in the record's selection algorithm and are written to the corresponding +output link (LNK0-LNKF). These output links can be database links or channel +access links; they cannot be device addresses. There are sixteen output links, one +for each desired output link. Only those that are defined are used. + +=fields LNK0, LNK1, LNK2, LNK3, LNK4, LNK5, LNK6, LNK7, LNK8, LNK9, LNKA, LNKB, LNKC, LNKD, LNKE, LNKF + +=head3 Selection Algorithm Parameters + +When the sequence record is processed, it uses a selection algorithm similar to +that of the selection record to decide which links to process.The select +mechanism field (SELM) has three algorithms to choose from: C<<< All >>>, +C<<>> or C<<< Mask >>>. + +=head4 Record fields related to the Selection Algorithm + +=fields SELM, SELN, SELL, SHFT, OFFS + +=head4 Fields Description + +B + +=menu seqSELM + +See L below; + +B + +This field can be initialized as a CONSTANT or as a LINK to any other record. SELN will fetch its value from this field when the seq record is processed. +Thus, when using I or I modes, the links that seq will process can be dinamically changed by the record pointed by SELL. + +B + +When B> this is the index number of the link that will be processed, used in combination with the C field: + + SELN = SELN + OFFS + + +I<(By default, the OFFS is initalized to ZERO)> + +When B> this field is the bitmask that will be used to determine which links will be processed by the seq record, +in combination with the C field: + + if (SHFT >= 0) + SELN = SELN << -SHFT + else + SELN = SELN >> SHFT + +I<(By default, the SHFT is initalized to -1)> + +=head4 B + +The first versions of seq record had DO, DOL, LNK and DLY fields starting with index ONE (DO1, DOL1, LNK1 and DLY1). +New version of the seq record now supports 16 links, starting by index ZERO (DO0, DOL0, LNK0 and DLY0). The SHFT and OFFS fields +were introduced to keep compatibility of old databases that used seq record with its links indexed from one onwards. + +B + +=head4 Selection Algorithms Description + +B + +The C<<< All >>> algorithm causes the record to process each input and output +link each time the record is processed, in order from 0 to 15. So when SELM is +C<<< All >>>, the desired output value from DOL0 will fetched and sent to LNK0, +then the desired output value from DOL1 will be fetched and sent to the location +in LNK1, and so on until the last input and output link DOF and LNKF. (Note that +undefined links are not used.) If DOLI is a constant, the current value +field is simply used and the desired output link is ignored. The SELN field is +not used when C<<< All >>> is the algorithm. + +B + +When the C<<< Specified >>> algorithm is chosen, each time the record is +processed it gets the integer value in the Link Selection (SELN) field and uses +that as the index of the link to process. For instance, if SELN is 4, the +desired output value from DO4 will be retrieved and sent to LNK4. If DOLI is +a constant, DOI is simply used without the value being fetched from the +input link. + +B + +When C<<< Mask >>> is chosen, the record uses the individual bits of the SELN +field to determine the links to process. When bit 0 of SELN is set, the value +from DO0 will be written to the location in LNK0; when bit 1 is set, the valud +from DO1 will be written to the location in LNK1 etc. Thus for example if SELN +is 3, the record will retrieve the values from DO0 and DO1 and write them to the +locations in LNK0 and LNK1, respectively. If SELN is 63, DO0...DO5 will be +written to LNK0...LNK5. + + +=head3 Delay Parameters + +The delay parameters consist of 16 fields, one for each I/O link discussed +above. These fields can be configured to cause the record to delay processing +the link. For instance, if the user gives the DLY1 field a value of 3.0, each +time the record is processed at run-time, the record will delay processing the +DOL1, DOV1, and LNK1 fields for three seconds. That is, the desired output value +will not be fetched and written to the output link until three seconds have +lapsed. + +=fields DLY0, DLY1, DLY2, DLY3, DLY4, DLY5, DLY6, DLY7, DLY8, DLY9, DLYA, DLYB, DLYC, DLYD, DLYE, DLYF + +=head3 Operator Display Parameters + +These parameters are used to present meaningful data to the operator. The +Precision field (PREC) determines the decimal precision for the VAL field when +it is displayed. It is used when the C<<< get_precision >>> record routine is +called. + +See L for more on the record name (NAME) and +description (DESC) fields. + +=fields PREC, NAME, DESC + +=head3 Alarm Parameters + +The sequence record has the alarm parameters common to all record types. +L lists other fields related to a alarms that are common to all +record types. + +=head2 Record Support + +=head3 Record Processing + +Routine process implements the following algorithm: + +=over + +=item 1. + +First, PACT is set to TRUE, and the link selection is fetched. Depending on the +selection mechanism, the link selection output links are processed in order from +LNK0 to LNKF. When LNKI is processed, the corresponding DLYI value is +used to generate a delay via watchdog timer. + +=item 2. + +After DLYI seconds have expired, the input value is fetched from DOI (if +DOLI is constant) or DOLI (if DOLI is a database link or channel +access link) and written to LNKI. + +=item 3. + +When all links are completed, an asynchronous completion call back to dbProcess +is made (see the Application Developer's Guide for more information on +asynchronous processing.) + +=item 4. + +Then UDF is set to FALSE. + +=item 5. + +Monitors are checked. + +=item 6. + +The forward link is scanned, PACT is set FALSE, and the process routine returns. + +=back + +For the delay mechanism to operate properly, the record is processed +asynchronously. The only time the record will not be processed asynchronously is +when there are no non-NULL output links selected (i.e. when it has nothing to +do.) The processing of the links is done via callback tasks at the priority set +in the PRIO field in dbCommon (see the Application Developer's Guide for more +information on call + +=cut + include "dbCommon.dbd" field(VAL,DBF_LONG) { prompt("Used to trigger")