Use Introduce; Specification; Setup; Appendix 1. Pi7000 Rs485 Communication Protocol - Powtran PI7800 User Manual

Appendix 1. PI7000 RS485 communication protocol
1.

Use introduce

This chapter introduces something about the install and handle of RS485
communication between inverter and PLC, PC, factory computer.
RS485 standard interface
l
can communicate with all computer
l
using multi-drop link system, can link more to 127 inverters
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completely isolated, and noise shield
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The user would use all types of RS232-485 inverter, if only the inverter had
"automatic RTS control" function inside.
2.

Specification

Communication function:
Items
Communication
baud rate
Interface
methods
System code
Data formula
Slave address
3.

Setup

Communication connection
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Link RS485 communication cables to inverter control terminals (SG+),
(SG-).
l when using RS232-485 transform, connect Inverter "SG+" to RS485 "T+"，
Inverter "SG-" to RS485 "T-".
l
After Confirming connection again, turn on inverter power.
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If connection is right, set communication parameters as following:
y11 baud rate: 0:1200, 1:2400, 2:4800, 3:9600, 4:19200, 5:38400;
y12 current inverter communication address 1~127 (If there are more than 1
inverters, don't use the same number);
When using RS485 running control methods, set F05=0/1/2(Keypad +
RS485/CAN)
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Specification
38400/19200/9600/4800/2400/1200 bps is
selectable
Asynchronism communication methods,
semiduplex
ASCII (8 bit)
1 start bit, 8 data bits, 1 stop bit, and no parity bit
1~127
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A 1. PI7000 RS485
PPENDIX COMMUNICATION PROTOCOL
System config
INV.#1
RS232/485
Converter
Comm.
Terminal
Thinkpad
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The number of inverter can be connected is no more than 127.
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Though the length of communication cable can add up to 1300m,
considering the stability, the length limit within 800m.
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All the control signal cable use the shielded cable, and link to the terminal
"SH".
4. Communication protocol
Communication structure is that the inverters use as slave and computer uses
as host.
Base format
Host command frame format
Frame Slave Host Command
header address command index
1 byte 2 bytes 2 bytes 4 bytes
Slave responsion frame format
Frame Slave Slave Command
header address responsion index
1 byte 2 bytes 2 bytes 4 bytes
Explain:
Setting data and responsion data may not exist in some frame.
1: Frame header
7EH="~".
2: Slave address
Slave address can be set by y12. A network has an only marked address,
and the range is 1~127.
00H＝0 means the broadcast communication address.
When sending, takes apart the slave address to higher 4 bits and lower 4 bits,
and converts to ASCII code, then sends higher 4 bits firstly.
For example: If the slave address is 08H, the system sends "0"＝30H，then
sends "8"＝38H。
3: Host command/slave responsion
The host sends the command, and the slave respond to the command.
When sending, takes apart the slave address to higher 4 bits and lower 4 bit,
and converts to ASCII code, then sends higher 4 bits firstly.
For example: If the slave address is 03H, the system sends "0"＝30H，then
110
INV.#2 INV.#n
Comm. Comm.
Terminal Terminal
Check Frame
Setting data
sum trail
4 bytes 2 bytes 1 byte
responsion Check Frame
data sum trail
4 bytes 2 bytes 1 byte