Omron CS1W-DRM21, CJ1W-DRM21 2 I/O Response Time, Refresh Time, Maximum I/O Response Time

Remote I/O Communications Characteristics Section 8-1

Slaves with More Than 8 Bytes of Input or Out put

Refresh Time

TRT = TOH + TBYTE-IN ⋅ BIN + TBYTE-OUT ⋅ BOUT [ms]
TOH :	Protocol overhead
TBYTE-IN :	The input byte transmission time
BIN :	The number of input words
TBYTE-OUT :	The output byte transmission time
BOUT :	The number of output words
Baud rate	TOH	TBYTE-IN	TBYTE-OUT
500 kbps	0.306 ms	0.040 ms	0.036 ms
250 kbps	0.542 ms	0.073 ms	0.069 ms
125 kbps	1.014 ms	0.139 ms	0.135 ms

For Input Slaves take BOUT to be 0, and for Output Slaves take BIN to be 0.

The refresh time is the time required for I/O data to be exchanged between the PC’s CPU Unit and the DeviceNet Unit. The CPU Unit’s cycle time is increased when a DeviceNet Unit is mounted, as shown below.

Processing item	Processing time
I/O refresh	DeviceNet Unit I/O refreshing time (ms)
	0.7 + 0.001 ⋅ the number of words refreshed (See note 1.)

Note 1. The number of words refreshed is the total number of words in the I/O area that are used by the Slaves, including any unused words between words actually used by the Slaves. For example, if there are only two Input Slaves with node addresses 1 and 5, the 5 input words for nodes 1 through 5 would be refreshed even though the input words for nodes 2, 3, and 4 are unused.

2.If message communications are being performed, just add the number of words used in message communications to the above number of words for whenever messages are being processed.

3.When the message communications are performed, an event execution time must be added to the PC cycle time.

4.For details about refresh time or PC cycle time, refer to operation manual of the PC.

8-1-2 I/O Response Time

Maximum I/O Response Time

Communications Cycle The maximum I/O response time will be as shown below if the DeviceNet Unit

Time ≥ PC Cycle Time takes in data immediately after I/O refreshing and if the communications cycle time is longer than the PC cycle time.

PC	Instruction	Instruction	Instruction
	execution	execution	execution
ON input data	Transfers to the	Takes into the
notice delayed	shared RAM
	when PC scan is PC's internal
	completed.	memory.

Communications cycle

Slave

192