Section 1—32-Bit Modbus Protocol (Default)
Introduction
The communications protocol for the Scanner 3100 is in accordance with Modicon, Inc. RTU Mode Modbus as de-
scribed in
Modicon Modbus Protocol Reference Guide
, PI-MBUS-300 Rev. J, June 1996. All registers are implemented
as 4X or holding registers. Reading of registers is implemented via function code 03H (Read Holding Registers). Writing
to registers is implemented via function code 10H (Preset Multiple Registers). The instrument provides Enron Modbus
compliant downloads for interval, daily and event records. For details on Enron Modbus, refer to
Specifications and Re-
quirements for an Electronic Flow Measurement Remote Terminal Unit for Enron Corp
., Dec. 5, 1994.
Scanner 3100 Modbus Maps
Scanner 3100 protocol is supported by three pre-defined register maps and a Cameron software application, ScanMap,
for customizing maps to suit individual host requirements.
• Two Modbus maps are preloaded in the Scanner 3100:
– A 32-bit Enron Modbus map includes registers for the Scanner 3100 and up to 20 slave devices. These registers
are described in this section. This map is also stored in ScanMap software (see
– A 16-bit Modbus map includes registers for the Scanner 3100 and up to 20 slave devices and presents values
in a 16-bit standard Modbus format. These registers are described in
Section 2—16-Bit Modbus Protocol
. This
map is also stored in the ScanMap software (see
below).
• A third Modbus map—a version of the 32-bit Enron Modbus map without slave device registers (“base unit” map)—is
available for download from Cameron’s ScanMap software. See S3100_MAP_TEMPLATE_ ENRON_BASE_UNIT
below for download instructions.
Table 1.1—Predefined Modbus Maps
Pre-Defined
Modbus Map
Scanner
3100
Registers
Enron
History &
Events
Slave
Device
Registers
Preloaded
in Scanner
3100
ScanMap Template Name
32-Bit Enron Modbus
S3100_MAP_TEMPLATE_
ENRON_DEFAULT
16-Bit Modbus
—
S3100_MAP_TEMPLATE_
MODBUS
Modified 32-Bit
Enron Modbus
—
—
S3100_MAP_TEMPLATE_
ENRON_BASE_UNIT
User-Defined Maps (ScanMap Software)
ScanMap software allows a user to create a custom Modbus register map by modifying the contents of a pre-defined map
or using a blank template and selecting individual registers. ScanMap includes databases for all three of the pre-defined
Modbus maps described above. Each can be used as-is, or modified with user-specified registers and units.
See
for the names of available register map templates.
ScanMap Download
To download ScanMap and/or the ScanMap User Manual, visit Cameron’s Measurement website at
, select
CAMERON Flow Computer Scanner 3100
, and click the link for the ScanMap install or
manual
7
Scanner 3100 Modbus Protocol
Section 1
Содержание Scanner 3100
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