Mitsubishi Electric MELSEC-L Series - Appendices; Appendix 1 Processing Time

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APPENDICES

Appendix 1 Processing Time

Calculate the minimum processing time for each function using the expressions below. Note that the processing time

may become longer depending on the load factor on the network (how congested the line is), the window size of each

connected device, the number of connections, and system configuration. Use the values obtained from the

expressions as a guideline for the processing time when communications are performed in only one connection.

(1) Minimum processing time of communications using a fixed buffer

(communications between the E71s)

(a) Procedure exists

Tfs = St + Ke + (Kdf  Df) + Sr

(b) No procedures

Tfs = St + Ke + (Kdf  Df)

[Calculation example]

The time between the E71 sending 1017-word data of a binary code and it completing the sending when the

E71 communicates with another E71 in TCP/IP with the "Procedure Exist" method (unit: ms)

Assume that the scan time on the sending side is 10ms, and the scan time on the receiving side is 8ms.

• 28.6561 (ms)  10 + 7.3 + (0.0033  1017) + 8

Tfs The time from the start of sending to the completion of sending (unit: ms)

St Sending station scan time

Ke, Kdf Constant (Refer to the table below.)

Df Number of send data words

Sr Receiving station scan time

Item

LJ71E71-100

TCP/IP communications UDP/IP communications

Ke Kdf Ke Kdf

Communications using a binary code 7.3 0.0033 6.2 0.0040

Communications using an ASCII code 7.3 0.0082 6.2 0.0081