Honeywell HC900 - Manual (Page 12)

Introduction
Modbus/TCP Interface
4 HC900 Hybrid Controller Communications User Guide Revision 10
12/07
Ethernet 10/100Base-T Network Connections
Ethernet 10/100Base-T networks operating at 10/100MB/sec. are supported. A typical network arrangement is as
shown below.
PC HMI
C70
E1
E2
I/O
S2
S1
Run/Pgm
Run/Pgm Run Pgm
C70
E1
E2
I/O
S2
S1
Run/Pgm
Run/Pgm Run Pgm Run/Pgm
Run/Pgm Run Pgm
C70
E1
E2
I/O
S2
S1
Run/Pgm
Run/Pgm Run Pgm
C70
E1
E2
I/O
S2
S1
Run/Pgm
Run/Pgm Run Pgm Run/Pgm
Run/Pgm Run Pgm
C70
E1
E2
I/O
S2
S1
Run/Pgm
Run/Pgm Run Pgm
C70
E1
E2
I/O
S2
S1
Run/Pgm
Run/Pgm Run Pgm Run/Pgm
Run/Pgm Run Pgm
C70
E1
E2
I/O
S2
S1
Run/Pgm
Run/Pgm Run Pgm
C70
E1
E2
I/O
S2
S1
Run/Pgm
Run/Pgm Run Pgm Run/Pgm
Run/Pgm Run Pgm
RS232/RS485
Serial Ports S1 & S2
Ethernet Host Port E1
Ethernet Host Port E2
I/O Port
Switch
To other subnets
IP Address
193.142.165.46
IP Address
193.142.165.45
10/100Base-T
10/100Base-T
C70
E1
E2
I/O
S2
S1
Run/Pgm
Run/Pgm
Run Pgm
C70
E1
E2
I/O
S2
S1
Run/Pgm
Run/Pgm
Run Pgm
Run/Pgm
Run/Pgm
Run Pgm
Figure 1-2 Ethernet 10/100Base-T Network Connections
Setting Up the Modbus/TCP Double Register Format
The HC900 predominantly uses an IEEE floating point format for communicating data to software applications
providing Modbus/TCP protocol communications drivers. A floating point value is sent as (2) consecutive 16-bit
registers, each register of which consists of two 8-bit bytes. Some software packages require the registers and bytes
to be sent in a certain order. The controller can be configured to deliver the data in four different byte orders.
The Hybrid Control Designer software tool allows this order to be selected as follows:
1. Using the Utilities Worksheet in the HC Designer software, access the Set Controller Network
Parameters button and make the selection to change the Modbus TCP Double Register Format (middle
radio button).
2. With the Port selected for downloading this order (using a COM port or Network port), select the
appropriate byte order format if the default (FP B) is not appropriate for the application. See Table
3-1, page 10.
3. Select Next and verify (by the response in the dialog box) that the change has been made in the
controller. This order can be changed in the RUN mode.
The Modbus TCP double register transmission format selection, FP LB “Little Endian Byte-Swapped”, would be
selected for interface to most third party software packages which use this format as standard. The default, FP B
“Big Endian” is used with SpecView32 or Honeywell’s PlantScape/Experion/EBI software and follows the
“Honeywell” default format of other control and recording products. It should be noted that most PC software
packages offer a register (word) swap selection in their driver package anyway, so there should never be an
incompatibility.