PowerFlex 4_40 with MicroLogix1100 on ModbusRTU_broadcast

Overall Description
<strong>PowerFlex</strong> 4 class drives can be controlled over Modbus RTU using the built-in serial interface (DSI
connector) on the drive. This application note details the Micrologix 1100 plc being used as Modbus
RTU master to control <strong>PowerFlex</strong> 4 class drives using broadcast control.
To control a drive on Modbus RTU, each drive needs to use a seperate message (MSG) command for
the Logic Control word, Speed Reference word, Logic Status word and Speed Feedback word. With a
large number of drives on the network, it can take a significant period of time before the MSG instruction
for the last drive to start, is executed. Modbus RTU supports a global broadcast feature, whereby one
MSG instruction is used to write the same value to same register in every drive, by using the Modbus
RTU command ‘16’ to the Modbus address ‘0’. This means that we could broadcast the Logic Command
word to start /stop all the drives together, or provide a common speed reference to the drives. This could
significantly reduce the time to control a number of drives on the network.
The MicroLogix 1100 has an embedded multi functional LCD for on-line editing, and EtherNet/IP for
connecting to an peer to peer network or our programming PC. The 2 <strong>PowerFlex</strong> drives being used in
this test are a <strong>PowerFlex</strong>4 setup as Node 1, and a <strong>PowerFlex</strong>4M setup as Node 2.
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Date 05/09/2007
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!

Equipment used for test
MicroLogix 1100 1763-L16AWA
RSLogix500 CPR ver 7 and RSLinx ver 2.51
The <strong>PowerFlex</strong> 4 class drives need a minimum firmware revison to support Modbus RTU code ‘16’:
<strong>PowerFlex</strong> 4 – frn 4.02
<strong>PowerFlex</strong>4M – frn 1.01
<strong>PowerFlex</strong><strong>40</strong> – frn 3.03
<strong>PowerFlex</strong><strong>40</strong>P and <strong>40</strong>0 have not been tested
1761-CBL-PM02 ser B, PC to MicroLogix programming cable
1763-NC01 The phoenix plug pin connectons are the same as the RS485 on the NET-AIC
AK-U0-RJ45-TB2P 2 position terminal block
Modbus RTU requires a 120 Ohm terminator at each end of the network. Putting a link between pins 1
& 2 of the terminal block terminates one end, and a 120 Ohm resistor is screwed into the 2 position
terminal block at the other end.
Drive Parameter setup
Drive parameters need to be setup as below. When para change complete, cycle the drive power.
Parameter PF4,
<strong>40</strong>, <strong>40</strong>P, <strong>40</strong>0
Parameter PF4M Details Value
P36 P106 Start source from Network 5
P38 P108 Speed reference from network 5
A103 C302 Comm data rate set at 19200kb 4
A104 C303 Comm node address set to 1 1 & 2
A107 C306 Comm format set to RTU 8-N-1 0
MicroLogix Setup
The MicroLogix 1100 needs to be setup first using the serial cable 1761-CBL-PM02 on channel 0.
If when connecting to the ML1100 an error is reported that it is not an SLC, then upgrade RSLogix to ver
7 and RSLinx to ver 2.50.
Startup RSLogix500 and create a new project <strong>with</strong> the Micrologix 1100
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Select channel configuration
Setup Channel 1 EtherNet IP address and subnet. Make sure you uncheck the BootP enable, and then
download to the controller.. To make the IP address stick, cycle the power on the ML1100.
Now we have the IP address in the ML1100, then we can reconfigure our computer and go-line using
the EtherNet connection. This will allow us to remove the serial cable 1761-CBL-PM02 on channel 0,
and use plug in the 1763-NC01 and reconfigure Channel 0 for Modbus RTU.
Additionally ensure that the settings <strong>with</strong>in the ML1100 are setup on the LCD:
ESC …. Scroll down ….. Advance Set …… DCOMM Cfg = disable
Change to cable 1763-NC01, and select the channel configuration as before.
Setup channel 0 to be Modbus RTU master at 19200 <strong>with</strong> no parity
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Make sure you adjust the protocol control
from the default No handshaking to No
handshaking (485 network) and the
timeouts /delays to 20ms.
Download configuration to controller using
the EtherNet connection.
Once the ML1100 is in run mode, both
COMM0 and COMM1 will be flashing fast
The ML1100 communicates <strong>with</strong> the drive using MSG instructions on Modbus RTU. So we create a
number of MSG instructions for the Logic control, reference , logic status and drive speed feedback..
The MSG instructions are cascaded so that they all operate in sequence. This scheduling of MSG
instructions is necessary to ensure that each instruction receives its hand-shake and completes
properly.
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Date 05/09/2007
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The logic command data will be stored in N15:0, so configure the message to send N15:0 to the Modbus
address for the logic command at 8192 (this means modbus sends to address 8193). Notice that we use
the command ’16 Write Multiple Registers’, and the Slave node address is ‘0’.
When the program is downloaded, we can go online and change the logic word to start and stop the drive.
Double click on the N15 data file, and change the value of N15:0 to 2. The drives will now start.
Changing the value of N15:0 to 1 will stop the drives.
The bits that are part of the Logic Control word are:
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The plc MSG 11:1 broadcasts the reference to all drives on address 8194 via N15:1. Therefore change
the value of N15:1 between 0 to 500 = 50.0Hz.
The broadcast message is a write MSG to all the drives on the network, typically used for the Logic
Control and reference words. Other drive registers would be read <strong>with</strong> a single MSG ’03 Read Holding
Register’ command.. The most important registers are:
Address Read/Write Description
8192 Write Logic Command
8193 Write Reference 0 to 500 = 0-50.0Hz
8448 Read Logic Status
8449 Read Error codes
8450 Read Frequency Command – Parameter 1
8451 Read Output Frequency – Parameter 2
Up to 8477 Read Step Logic status – Parameter 28
Remember to add 1 to the address when used in the MSG setup screen.
The program associated <strong>with</strong> this test is called
MODBUS_RTU_WITH_MICROLOGIX_1100_AND_POWERFLEX_4_DRIVES_BROADCAST.RSS
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Date 05/09/2007
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