Omron CJ1W-DRM21, CS1W-DRM21 operation manual Communications Time/Slave

Remote I/O Communications Characteristics Section 8-1

Communications Cycle Time Calculation

Use the equations shown below to calculate the communications cycle time (TRM) for a network with one Master. Note that if the result of this calculation is less than 2 ms, the actual communications cycle time will be 2 ms.

TRM= Σ (Communications time per Slave)

+High-density Unit processing time

+Explicit message processing time

+COS/Cyclic connection time (ms)

+0.01 ⋅ N + 1.0 [ms]

Communications Time per Slave:

This is the communications time required for a single Slave.

“Σ (Communications time per Slave)” represents the total of the “Communica- tions time per Slave” for all the Slaves in the network.

High-density Unit Processing Time:

3.5 ms

This is added if there are any Slaves in the network that use at least 8 bytes for input, output, or both.

Explicit Message Processing Time:

(0.11 ⋅ TB) ⋅ n [ms]

Only added when explicit communications (sending or receiving) are per- formed.

n= Number of explicit messages (both sending and receiving) that occur in one cycle time

TB = The baud rate factor

(500 kbps: TB = 2; 250 kbps: TB = 4; 125 kbps: TB = 8)

COS/Cyclic Connection Time:

{(0.05+0.008 ⋅ S) ⋅ TB} ⋅ n (ms)

S:Total number of inputs and outputs in the COS/cycle connection (bytes) TB: The baud rate factor

(500 kbps: TB = 2; 250 kbps: TB = 4; 125 kbps: TB = 8)

n:Number of nodes occurring simultaneously within 1 communications cycle time in the COS/Cyclic connection

N: Number of Slaves

Communications Time/Slave

Output Slaves with Less Than 8 Bytes of Output

The communications time per Slave is the communications time required for a single Slave.

The following equations show the communications time/Slave (TRT) for each kind of Slave Unit.

TRT = 0.016 ⋅TB ⋅ SOUT1 + 0.11 ⋅ TB + 0.07 [ms] SOUT1 : The number of Output Slave output words

TB : The baud rate factor

	(500 kbps: TB = 2; 250 kbps: TB = 4; 125 kbps: TB = 8)
Input Slaves with Less	TRT = 0.016 ⋅TB ⋅ SIN1 + 0.06 ⋅ TB + 0.05 [ms]
Than 8 Bytes of Input	SIN1 : The number of Input Slave input words
	TB :	The baud rate factor

Mixed I/O Slaves with Less Than 8 Bytes of Input or Output

(500 kbps: TB = 2; 250 kbps: TB = 4; 125 kbps: TB = 8)

TRT = 0.016 ⋅ TB ⋅ (SOUT2 + SIN2) + 0.11 ⋅ TB + 0.07 [ms] SOUT2 : The number of Mixed I/O Slave output words

SIN2 : The number of Mixed I/O Slave input words

TB : The baud rate factor

(500 kbps: TB = 2; 250 kbps: TB = 4; 125 kbps: TB = 8)

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