Mitsubishi Electric MELSEC iQ-R Series User Manual page 232

Remarks
■When changing the no-reception monitoring time (timer 0)
Set the no-reception monitoring time (timer 0) to the following number of bytes or greater.
No-reception monitoring time (timer 0) = 1 +
(Round up fractions below decimal point.)
Td : Maximum delay time for target device output processing (ms)
Vbps: Transmission rate (bps)
Ex.
Calculation of no-reception monitoring time (timer 0)
Transmission rate (Vbps) : 9600 bps
Maximum delay time for target device output processing (Td) : 50 ms
No-reception monitoring time (timer 0) = 1 +
In this case, actual monitoring time is as shown below:
*1
41 bytes  12  9600  1000 = 51.25 ms
*1 Number of transmit bits per byte (Fixed)
■When changing the no-reception monitoring time (timer 0) for data communication with a
target device through C24 RS-422/485 interface
Set the no-reception monitoring time (timer 0) to the following number of bytes or greater.
No-reception monitoring time (timer 0) = 1 +
Td : Maximum delay time for target device output processing (ms)
T1 : Target device side hardware gate OFF time (ms)
Vbps: Transmission rate (bps)
10 CHANGING DATA COMMUNICATION MONITORING TIME
230
10.1 No-reception Monitoring Time (timer 0) Setting
Td × Vbps
12000
50 × 9600
= 41 bytes
12000
(Td + T1) × Vbps
12000
(Round up fractions below decimal point.)