Filter
Top Products
MODBUS TEST 10-3
MON2000
JULY 2010 Comparison of Modbus Protocols
10.2.1 Comparison of Modbus Protocols
MON2000 software and the WinMB program
accommodate two different Modbus protocols:
SIM_2251 and User_Modbus. For each protocol,
separate Modbus registers are reserved.
Thus some settings for MON2000 and WinMB
depend on which Modbus protocol is used.
The protocol you need depends, ultimately, on
the hardware used for data acquisition from the
GC Controller Modbus register contents.
The following comparison should help clarify
the differences between these protocols as well
as the utility of each.
Table 10-1 Comparison of SIM_2251 and User_Modbus Protocols
SIM_2251 User_Modbus
serial slave port serial slave port
modified protocol that allows floating point
numbers to be transmitted over Modbus via
2251 emulation slave type
standard Gould protocol that accommodates
PLC Emulation LO-HI (PLC-LH)
most register contents are predefined; some
registers can be user-defined
predefined Boolean (coils)
user-defined Numeric (registers)
data types are predefined for registers 1000 to
9000
data types are user-defined
variables assigned to registers can be listed in
the PC Config Report (for instructions, see
Section 2.16.3; for an example report, see
Appendix A). See Appendix F for more detail
about individual registers.
variables assigned to registers can be listed in
the PC Config Report (for instructions, see
Section 2.16.3; for example report, see
Appendix A)
When using WinMB, set Register Mode to
“DANIEL” to view register contents.
When using WinMB, set Register Mode to
“PLC- LH” or “PLC-HL” to view register
contents.
It is not necessary to assign scales to regis-
ters.
It may be necessary to assign scales to regis-
ters, to convert floating point values to whole
integer representations.