Front Panel Switches
Original instructions
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Front Panel Switches
Two three-position slide switches are located on the front of the CPU. The left switch is used for memory protection when in the top position and no memory protection in the middle and bottom positions. The switch on the right is used to select the Comm parameter settings for the Modbus (RS-232) ports.
NOTE: The memory switch selection is taken into account immediately.
NOTE: The modbus switch selection is taken into account after a Power off/on of the Quantum PLC
WARNING
UNINTENDED EQUIPMENT OPERATION
Do not allow an automatic backup restore upon cycling power to the PLC. The backup restore function reloads in the PLC memory the version saved on the memory card, that can be different than the one that was running before the power off.
Failure to follow these instructions can result in death, serious injury, or equipment damage.
ASCII Comm Port Parameters Table
Setting the right slide switch to the top position assigns ASCII functionality to the port. The following ASCII Comm parameters are preset and cannot be changed:
ASCII Comm Port Parameters
Transmission Speed (Baud)
2,400
Parity
Even
Data Bits
7
Stop Bits
1
Device Address
Rear panel rotary switch setting
NOTE: The CPU hardware defaults to bridge mode when the right slide switch is set to RTU mode. When networking controllers, a panel device connected to the CPU Modbus port can communicate with the controller to which it is connected, as well as log into any nodes on the Modbus Plus network.
RTU Comm Port Parameters
Setting the right slide switch to the middle position assigns remote terminal unit (RTU) functionality to the port; the following comm parameters are set and cannot be changed.
RTU Comm Port Parameters
Transmission Speed (Baud)
9,600
Parity
Even
Data Bits
8
Stop Bits
1
Device Address
Rear panel rotary switch setting
Valid Comm Port Parameters Table
Setting the right slide switch to the bottom position gives you the ability to assign comm parameters to the port in software. The following parameters are valid.
Item
Valid Comm Port Parameters
Mode
ASCII or RTU
Transmission Speed (Baud)
19,200
9,600
7,200
4,800
3,600
2,400
2,000
1,800
1,200
600
300
150
134.5
110
75
50
Data Bits
ASCII: 7 Bit
RTU: 8 Bit
Stop Bits
1 / 2
Parity
Enable/Disable Odd/Even
Device Address
1 ... 247