Edwards SCU-800 - Example of Command Sending Process; Example of Answer Receiving Process

SCU-800 Control Unit for Turbomolecular Pump
MT-49E-101-G
Page 80
5
SERIAL COMMUNICATION
PROTOCOL
This procedure is not necessary
if total block N = 1.
*1 When using RS485 to communicate,
switch the PC side from sending state to
receiving state within 5 sec.
*2 When using RS485 multipoint connection,
also an address is incorrect.
Send command (N blocks)
Block number: k = 1
k = k + 1
Yes
No (Timeout 2sec)
Command sending success
Send block (k)
Retry?
Command sending failure
No
*2
Yes
No
Yes
No
Yes
Block check:
k = N?
*1
Acknowledge
received?
ACK received?
Figure 47 - Example of command sending process
This procedure is not necessary if N = 1.
*1 When using RS485 multipoint connection,
also an address is incorrect.
*2 When using RS485 to communicate, send after 1
msec or more progress from block data received.
*3 When using RS485 multipoint connection,
send with address data.
Receive answer (N blocks)
Correct LRC
k = k + 1
ETX received?
Block (k) received?
Yes
Answer receiving success
Send ACK
Retry?
Answer receiving failure
Send NAK
Block number: k = 1
No
*1
No
Yes
No
Yes
*2, *3
No (Timeout 2sec)
Figure 48 - Example of answer receiving process