YASKAWA iQpump Series Programming Manual page 81

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H5 Serial Communications Setup
This section explains the individual functions used in special applications involving Modbus Communications.
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Using Modbus Communication
Serial communication can be performed with Programmable Logic Controllers (PLC's) or similar devices using the Modbus protocol.
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Modbus Communication Configuration
Modbus communication is configured using 1 master (PLC) and a maximum of 31 slaves. Serial communication between master and
slave is normally initiated by the master and responded to by the slaves.
The master performs serial communication with one slave at a time. Consequently, the slave address of each slave must be individually
set, so that the master can perform serial communication using that address. Slaves receiving commands from the master perform the
specified functions, and send a response back to the master.
Figure 1.76
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Communication Specifications
The Modbus communication specifications are shown below:
Item
Interface
Communications Cycle
Communications Parameters
Communications Protocol
Number of Connectable Units
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Communication Connection Terminal
Modbus communication uses the following terminals: S+, S-, R+, and R-. The terminating resistance must be turned ON only if the
iQpump drive is at the very end of the Serial Communication chain. Set the terminating resistance by turning ON pin 1 of switch S1 On
the Drives terminal board. Switch S1 is located directly above the left most relay module.
YASKAWA TM.iQp.02 iQpump Drive Programming Manual
Master
Figure 76 Example of Connections between Master and Drive
Table 19 Modbus Communication Specifications
RS-422, RS-485
Asynchronous (Start-stop synchronization)
Baud rate:
Data length:
Parity:
Stop bits:
Modbus
31 units max.
Slaves
iQpump
iQpump
Specifications
Select from 1200, 2400, 4800, 9600, and 19200 bps.
8 bits fixed
Select from even, odd, or none.
1 bit selected
iQpump
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