P
RO
V
U
™ PD6088/PD6089 Modbus
®
Scanner
Instruction Manual
24
Serial Communications (
serial
)
The scanner is equipped with RS-485 Modbus RTU
serial communications.
The
Serial
menu is used for programming the
Scanner ID, Baud Rate, Transmit Delay, Parity, and
Byte-to-Byte Timeout parameters.
The scanner may be connected to a PC for initial
configuration via the on-board micro USB connection.
For ongoing digital communications with a computer
or other data terminal equipment, an RS-232, or
RS-485 option is required; see
Ordering Information
on page
6
for details.
•
DO NOT
connect any equipment other than
Precision Digital’s expansion modules, cables, or
scanners to the RJ45 M LINK connector.
Otherwise damage will occur to the equipment
and the scanner.
When using more than one scanner in a multi-drop
mode, each scanner must be provided with its own
unique address. The scanner address (Scan ID) may
be programmed between 1 and 247.
The transmit delay may be set between 0 and 4999
ms; this value must be less than (Poll Time/# of PVs).
The parity can be set to even, odd, or none with 1 or 2
stop bits.
Changes made to the Serial menu are initialized after
exiting the Serial menu.
When setting up the scanner to run on a Modbus
system, the devices must be programmed with
matching Baud Rate and Parity. Failure to match up
the network devices’ parameters may result in
communication breaks.
Notes:
1. The byte-to-byte timeout setting may be
adjusted to fix communication errors with
slow devices.
2. The Transmit Delay of the Master must be
greater than the Snooper or the slave
devices being polled.
3. When using the M-Link to connect to a
Modbus network, the PD6088/PD6089
cannot be used as a Master, but can be
used as a Snooper or as a Slave. In order to
use the PD6088/PD6089 as a Master, the
scanner must connect to the Modbus
Network via the three-wire terminal
connector on the back of the scanner.
