Helios PD2-6080/PD2-6081 Modbus
®
Scanners
Instruction Manual
31
Scanner Mode Selection
Operating Modes (
nmode
)
The
Mode
menu is used to select how the scanner is
to function:
1. Master: Reads a slave device, scales the data
from it, displays the result, and operates the
relays and 4-20 mA output. The Master polls from
1 to 16 process variables from 1 to 16 slave
devices. The Master processes and displays PV1
through PV16 and alternately displays the
variables being polled.
2. 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.
3. Slave: Read and controlled by a master device
(PLC, DCS, etc). The data sent to it by the
master is scaled, displayed, and used to operate
the relays and 4-20 mA output.
The Master mode requires additional parameter
selection to specify how the slave device is to be read
and how to interpret the data.
Press
Menu
to enter Scanner Programming. Press
the
Enter
button to access any menu or press
Up
arrow button to scroll through choices. Press the
Menu
button to exit at any time and return to Run
mode.
How to Enable Process
Variables (PVs)
In Master or Snooper Mode, navigate to the
PV
Number
menu and press ENTER. From there, the
user can scroll through all of the sixteen available
PVs. In order to enable a specific PV, simply press
ENTER to access the desired PV, then scroll to
ENABLE and press ENTER (Follow the same course
of action for disabling PVs).
Enter the Slave ID of the device being polled by the
Master, followed by the Function Code, Register
Number, Data Type, and Byte Order. Analog input
channels must be assigned a Slave ID corresponding
to the input to be read as indicated here:
•
Ch A = 256 (mA) or 257 (V)
•
Ch B = 258 (mA) or 259 (V)
Once the desired PVs are enabled, navigate to the
Setup
menu and enter the PV Setup in order to select
the PV tag, units, format, and decimal point
parameters, as well as to scale the PVs.
Once the user has scaled the final PV, the scanner
automatically goes to the
Display Setup
menu to
access line 1 and 2 display assignments.
By default, display line 1 is assigned to
Display PV
(
d pV
) and line 2 to display the
Tag
(
d tag
) for the
corresponding PV.
It is possible to display PVs & Tags on line 1 and 2
simultaneously by selecting
Tag & PV Number
(
tag.pVn
). Display line 1 is setup by default to display
PV & tag for PV1, 3, 5, 7; while line 2 is setup by
default to display PV & tag 2, 4, 6, 8. These can be
changed by the user to display any or all PVs.
Program either display line 1 or 2 to show the desired
parameters and press ENTER. See
