P
RO
V
U
™ PD6088/PD6089 Modbus
®
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Instruction Manual
7
Specifications
Except where noted all specifications apply to
operation at +25°C.
Operating Modes
Master
Processes data read from Modbus RTU
slave devices. It polls up to 16 process
variables from 1 to 16 slave devices. The
Master is capable of scanning the selected
PVs, scaling the data, triggering relays,
performing math operations, and driving
the analog outputs.
Snooper
Listens to the Modbus traffic and picks up
a specific register or registers being polled
by a master device from a specific slave
device and processes the data being read.
The Snooper mode handles the data the
same way as the Master.
Slave
Processes data sent to it from a Modbus
RTU master device.
Note: The relays and the 4-20 mA outputs are functional in
all modes.
Master & Snooper Settings
PV Number
PV1
–PV16 Enable or disable the process
variables to be polled by the Master.
Slave Id
Assign the slave ID or address (1-247)
containing the process variables to be
displayed by the selected PV.
Function
Code
Select which Modbus function code (03, 04,
or 65) to use in reading the slave device.
Register
Number
5 digit: 30001-39999, 40001-49999, or
1-65,536
6 digit: 300001-365536 or 400001-465536
(Function Code 65 N/A here)
Specifies which register(s) to read in the
slave device. Range is dependent on
Function Code selection (65, 04, or 03) and
digits selection (5 or 6).
Data Type
Select the data format that the slave device
uses. Select between Short integer (2 byte),
Long integer (4 byte), or floating point
(4 byte), Signed or Unsigned (integer only)
and byte order: 1234, 4321, 2143, or 3412
(big-endian vs. little-endian, or swapped).
Poll Time
1.0 to 99.9 sec. Time between read-
commands (Master mode).
Slave
Response
Timeout
0.0 to 99.9 seconds: Time allowed for the
slave to respond before the scanner
generates a communication break
condition. The master polls the slave 3
times before starting the response timeout
timer.
Slave/Snooper mode: Time the scanner will
wait for new data before going into break
condition.
Slave mode: Programming 0 disables the
timeout; the last value received will be
displayed indefinitely.
Communica-
tion Break
Displays
brEAK
after the Master has polled
the slave device 3 times and the response
timeout has elapsed. The Snooper and
Slave modes go into break condition after no
new data is received within the response
timeout window. Relays can be programmed
to go on, off, or ignore the break condition.
The analog outputs can be setup to
generate a fixed mA current when a break
condition is detected.
PV Settings
Tag & Units
6-character, independent tag and units for
each PV and math channel
PV Format
PD6088 default: Decimal format
PD6089 default: FT & IN, 1/8
th
or 1/16
th
;
decimal format may be selected for line 2
indication.
Display
Decimal
Point
Up to five decimal places or none:
d . ddddd
,
dd . dddd
,
ddd . ddd
,
dddd . dd
,
ddddd . d
,
or
dddddd
Float
Decimal
Point
Select the number of decimals to use for
the floating point data expected from the
slave or master device (this is independent
from the display decimal point selection).
PV & Math
Scaling
All PVs and math channels may be scaled
to represent the input data in any
engineering unit.
Example: Level transmitter = 999.999
inches; to display in Ft-In-1/16
th
scale input
2 to display 83 Ft
– 4 In – 0/16
th
.
Display Settings
Scan Mode
Automatic: 1.0 to 99.9 sec
Manual: Front panel or digital inputs
Go on alarm: Continues scanning after an
alarm is detected
Stop on alarm: Goes to the alarmed PV
and stops scanning; press Scan to resume
scanning.
Display
Scan Rate
Master/Snooper: 1 PV/second to 1 PV
every 99.9 seconds
Slave: Dependent on master device
(e.g. PLC)
Note: The display scan rate is independent
of the poll time.
Display
Assignment
Display line 1 may be assigned to PV
(process values), Ch-C (math channel), PV
& units, tag & PV, tag-PV-units, C & units,
tag-C-unit, Set point 1-8, max/min PV,
max/min C.
Line 2 may be assigned to all of the above,
tag, tag & units, or off.
The tag and units are displayed alternately
for 2 seconds max, when selected.
Different tags & PVs may be selected to
display on line 1 & 2 at the same time.
