Example Of Answer Resending Process; Example Of Command Sending During Answer Data Reply - Edwards STP-iS1607 Series Instruction Manual

•
Always check the LRC checksum of answer data. When LRC checksum is incorrect, do not use
the data. When the incorrect data caused by noise is accepted, parameters might be set
5
unexpected values. In this case, the processing of the tool application may determine to be a
communication failure. When LRC checksum is incorrect, receive the answer data again according
to the following methods.
- Send "NAK" within 1500 msec after receiving the answer data, and then receive the answer
data again from SIM. However, when using RS485, send "NAK" at least 1 msec has passed
after receiving the answer data.
- Stop once the communication process, and try the communication process again.
PC
SIM
•
When sending the following command after receiving the answer data from the SIM, the following
command will be disabled.
Figure 45 - Example of response when the command is sent continuously
In addition, when using RS485, do not send commands while the answer data is sent from the
SIM. The crosstalk of sending data and receiving data will occur, and it causes communication
failure such as a flaming error.
MT-94E-001-C
Page 92
STP-iS1607 Series Turbomolecular Pump
Command
Send (A)
ACK Answer
Reply (A) Reply (A)
Figure 44 - Example of answer resending process
PC
Command
Send (A)
SIM
ACK
Reply (A)
The following command will be disabled
PC
Command
Send (A)
SIM
When using RS485, the crosstalk is happened if the
next command is sent during an answer data reply.
Figure 46 - Example of command sending during answer data reply
NAK NAK
Send (A) Send (A)
Answer
Reply (A)
The answer resending process by NAK sent
when LRC is incorrect value.
Command ACK
Send (B) Send (A)
Answer
Reply (A)
Command
Send (B)
crosstalk
ACK Answer
Reply (A) Reply (A)
ACK
Send (A)
Answer
Reply (A)