ProtEX PD8-6080/PD8-6081 Explosion-Proof Modbus
®
Scanner Instruction Manual
32
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 page 39 for details.
