Eurotech PCN-1001, User Manual

Page: 88 / 118

Test an RS485 connection and use the RS485_GUI PCN-1001 User manual
88
PCN-1001_UserMan_En_4.0
Polling
The master can poll a slave who answers with a message to the master. A poll is defined as a packet with:
TotalPacketNumber = 0
PacketNumber
= 0
DataLength = 0
Scenarios
The following charts are intended to give an idea of how the sequences are sent/received by the master and
slave devices:
Short Message to Slave
Polling
Receive Message
Send Message
[‘S’, ‘J’, 1, 1, x]
Send Message
[‘J’, ‘S’, 1, 1, y]
Master
“S”
Slave
“J”
Receive Message
Receive Message
Polling to Slave
[‘S’, ‘J’, 0, 0, 0]
Polling reply
[‘J’, ‘S’, 0, 0, 0]
Receive Message
Master
“S”
Slave
“J”