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4.3.16 In stru ment Com mands {P} = Z
Only Type 3 or Type 4 messages are allowed with this parameter. In the Type 3
message, the {DATA} field must be one of four five-digit numbers. The reply from the
instrument also contains the {DATA} field with the same content. When the master
device issues the Type 4 message, the instrument responds with the same {DATA} field
content. The commands corresponding to the {DATA} field value are:
00150 = Unlatch Alarm 1 (returns NAK if Alarm 1 is non-latching)
00160 = Reset Process Variable Maximum (to current PV value)
00170 = Reset Process Variable Minimum (to current PV value)
00180 = Reset Time Elapsed (to zero)
4.3.17 Scan Ta ble {P} = ]
The Scan Table operation takes the form of a Type 2 interrogation command which
accesses a set of information (held in the {DATA} element in the response). The
response would be in the form:
L {N} ] 25 aaaaa bbbbb ccccc ddddd eeeee A *
These digits are as described in Table 4-1 and comprise:
aaaaa The cur rent pro cess vari able value
bbbbb The cur rent maxi mum pro cess vari able value
ccccc The cur rent mini mum pro cess vari able value
ddddd The cur rent Time El pased value
eeeee The In stru ment Status (see Sub sec tion 4.3.15).
4.3.18 Er ror Re sponse
The circumstances under which a message from the master device is ignored are:
Par ity er ror de tected
Syn tax er ror de tected
Ti me out elapsed
Re ceipt of a Type 4 mes sage with out a pre ced ing Type 3 com mand mes -
sage.
Nega tive ac know ledge ments will be re turned if, in spite of the re ceived mes sage be ing
no tion ally cor rect, the in stru ment can not sup ply the re quested in for ma tion or per form
the re quested op era tion. The {DATA} ele ment of a nega tive ac know ledge ment will be
in de ter mi nate.
4 -8 November, 2000 OM067-4
Sec tion 4
1
8
-DIN Digi tal In di ca tor 59039
RS485 Se rial Com mu ni ca tions Product Man ual - Vol ume I
Bit 0: Alarm 1 Status
(0 = Active; 1 = Safe)
Bit 1: Alarm 2 Status
(0 = Active; 1 = Safe)
Bit 2: Alarm 3 Status
(0 = Active; 1 = Safe)
Bit 3: Change Indicator (1 = A parameter other than
Instrument Status or Process Variable has been
changed via the front panel since the last time the
Status Byte was read; 0 = No change has occurred).
Bit 5: Alarm 1 Latched
(1 = not latched, 0 = latched)
If non-latching, fixed at 1.
000 1