Yaskawa MP940 - Manual (Page 103)

MP940 Functions
4.2.5 Time Required for Transmission
4-10
The number of bits per character includes not only the number of data bits (8 or 7), but also
the number of start bits (1), stop bits (1 or 2), and parity bits (1 or 0).
Slave Processing Time
This is the time required, after the Slave has received the command message from the mas-
ter, for the slave to process the message and prepare a response message to the master, up to
the MEMOBUS port.
This time is related to the Machine Controller scan time and the number of coils, registers,
etc., designated in the command message, as well as to the number of processes performed
by the Machine Controller in one scan.
With the MP940, all functions are processed within one scan, so this time is equivalent to the
time required for one scan.
Modem Lag Time at the Slave
This is the time from when the modem at the slave receives a request-to-send (RTS) signal
from the slave until a clear-to-send (CTS) signal is returned to the slave.
With a Yaskawa modem this time is 5 ms or less, so it can basically be ignored. If no modem
is used at all, then this time lag will not exist.
Response Message Transmission Time
This is the time required for sending the response message from the slave’s communications
port. It can be calculated by means of the following equation:
The number of bits per character includes not only the number of data bits (8 or 7), but also
the number of start bits (1), stop bits (1 or 2), and parity bits (1 or 0).
Time for Master Processing of Response Message
This is the time required for a master such as a computer to process the response message
after receiving it from the slave.
This time depends on the processing time for the particular master.
It depends on the Machine Controller’s scan time, and normally requires one or two scans.
Transmission time = (ms)
(Number of characters in response message) x (Number of bits per character) x 1,000
Baud rate