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5.2 Setting the parity
You can set the parity either manually by using SW3 or via
software-defined settings.
Manual setting of parity
Default byte format (11 bits):
•
1 start bit
•
8 data bits (least significant bit sent first)
•
1 parity bit (even parity)
•
1 stop bit.
The default setting of the CIM 200 Modbus module is even parity
(1 stop bit). It is possible to change the parity using DIP switch
SW3. You can change the parity to no parity (2 stop bits). See fig.
6.
SW3
Parity
Fig. 6
DIP switch settings
Parity
Even parity, 1 stop bit
No parity, 2 stop bits
Software-defined parity and stop bits
When SW4 and SW5 are set to "software-defined", the value in
the holding registers at addresses 00009 and 00010 overrides
the setting of SW3. See figures
Software-defined parity
No parity [default]
Even parity
Odd parity
Software-defined stop bit
1 stop bit [default]
2 stop bits
The software-defined parity and stop bit values are stored in the
communication interface and remain after a power-off.
Before you set the parity and stop bits via software-
defined settings, you must set SW4 and SW5 to ON.
SW3
OFF
ON
5
and 6.
Value to set in register
00009
0
1
2
Value to set in register
00010
1
2
5.3 Modbus address selection
A Modbus slave on a Modbus network must have a unique
address from 1-247. Address 0 is reserved for broadcasting, and
is not a valid slave address.
Use the two hexadecimal switches, SW4 and SW5, to set the
transmission speed. See fig. 7.
Setting the Modbus address
Fig. 7
For a complete overview of Modbus addresses, see section
15. Modbus RTU rotary switch
You must set the Modbus address decimally from 1
to 247.
5.4 Termination resistor
The termination resistor is fitted on the CIM 200 Modbus module
and has a value of 150 Ω.
CIM 200 has a DIP switch with two switches: SW1 and SW2 for
cutting the termination resistor in and out. Figure
switches in cut-out state.
SW1 SW2
Cutting the termination resistor in and out
Fig. 8
DIP switch settings
Status
Cut in
Cut out
Default setting: Termination resistor cut out.
Cable length
We recommend the following maximum lengths:
Maximum cable length
Bits/s
Terminated cable
[m/ft]
1200-9600
1200/4000
19200
1200/4000
38400
1200/4000
To ensure stable and reliable communication, it is
important that only the termination resistor of the first
and last units in the Modbus network are cut in.
All switch settings are effective immediately after
setting the values, no power-off is needed.
SW6
SW7
addresses.
8
shows the DIP
SW1
SW2
ON
ON
OFF
OFF
ON
OFF
OFF
ON
Unterminated cable
[m/ft]
1200/4000
500/1700
250/800
9
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