MODBUS Interface
Verbatim Owner's Manual F-5
F.3.1 Before Calling Technical Service Assistance
Programmable Logic Controllers have been used for several decades for process
control applications. There is a large body of knowledge germane to using
PLCs. RACO assumes that the user needing to monitor a PLC network with the
Verbatim autodialer is already familiar with the PLCs being used for the
application. It may also be assumed that the user has access to a PLC expert to
help accurately identify the addresses of a PLC data register.
Before consulting the RACO Customer Service Department or your local
RACO Representative for assistance in installation and configuration, please
insure that the PLC details described in the next paragraph are readily available.
The user must have access to the PLC ladder logic program listing and know
the location and properties of all data table locations which will be monitored
by the Verbatim autodialer. Also the user must be able to determine the basic
operating parameters of the PLC communications channel. This means being
able to configure the PLC’s parameters such as the node address, baud rate, data
bits, parity and stop bits. Setting these parameters at the PLC may require the
use of a PLC Hand Held Terminal, or a Personal Computer running PLC
programming software available from the PLC’s manufacturer.
The MODBUS communications protocol is a Verbatim autodialer firmware
option and must have been properly configured at the factory. Parameters
concerning link, frame and packet-level interfaces are configurable in the field.
F.4 Programming for Remote Channels
F.4.1 Remote Channel Programming Overview
The Remote Channels (RCs) behave fundamentally the same as their physical
channel (PC) counterparts. Procedures for programming and recording
messages for remote channels are very similar to the procedures described in
the previous sections of this manual. There are some differences, however.
These differences will be discussed in this section.
In general, all Verbatim autodialer commands that operate on remote channels
will begin with the digit ‘4’. Commands that perform functions similar to non-
Remote Channel specific commands use the same key sequence, preceded by
the digit ‘4’.
K For example: to interrogate the alarm status for Physical Channel number
1 1, enter the command:
0 1 1 then <ENTER>
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