Mitsubishi Electric FR-A500 Instruction Manual page 140

7) Break in the cable detection
• If disconnection (communication stop) is detected between the inverter and computer as a result of
disconnection check, a communication error (E.PUE) occurs and the inverter output is shut off.
• Disconnection check is made when the setting is any of "0.1s" to "999.8s".To make disconnection check, it
is necessary to send data (control code refer to page 129) from the computer within the communication
check time interval. (The send data has nothing to do with the station number)
• Communication check is started at the first communication in the operation mode having the operation
source (PU operation mode in the default setting).
• When the setting is "9999", communication check (disconnection detection) is not made.
• When the setting is "0", communication from the PU connector cannot be performed.
Example: Pr. 122 = "0.1 to 999.8s"
Operation Mode
Computer
Inverter
Inverter
Computer
Pr.122
Communication
check counter
8) Sum check code
The sum check code is 2-digit ASCII (hexadecimal) representing the lower 1 byte (8 bits) of the sum
(binary) derived from the checked ASCII data.
(Example1)
Computer→Inverter
ASCII code→
*When Pr. 123 "waiting time setting" ≠ 9999, create the communication request data with no "waiting time" in the data format.
(The number of characters is decreased by 1.)
(Example2)
Inverter→Computer
ASCII code→
9) Error code
If any error is found in the data received by the inverter, its definition is sent back to the computer together
with the NAK code. (Refer to page 135.)
External
PU
Check start
Station
Instruction
ENQ
number
code
0 1 E 1
H05 H30 H31 H45 H31 H31
↓
H H H H H
30 + 31 + 45 + 31 + 31 + 30 + 37 + 41 + 44
H
=1F4
Sum
Station
STX Read data
number
0 1 1 7
H02 H30 H31 H31 H37 H37
↓
H H H H H
30 + 31 + 31 + 37 + 37 + 30
H
=130
Sum
131
Alarm(E.PUE)
Sum check
Data
code
1 0 7 A D F 4
H30 H37 H41 H44 H46 H34
H H H H
Sum check
ETX
code
7 0 3 0 ←Binary code
H30 H03 H33 H30
H
PARAMETERS
←Binary code
4