System Startup Time - Omron CJ Series Operation Manual

5 Operation
The total I/O response time is the sum of all components:
T = T + T
IO IN
5-5-6

System Startup Time

 Startup Time Definition
The system startup time is the delay from the time the CJ1W-PRM21 PROFIBUS Master Unit is
turned ON, or reset, until I/O data exchange with all slave devices has been established. For this,
the following is assumed:
• The Master Unit has been configured to go to OPERATE mode if the CPU mode is set to RUN
mode.
• All slave devices are powered up and initialized before the Master Unit is turned ON.
• All slave devices are assumed to go to I/O data exchange without delays.
The total system startup time is the sum of the following components:
• Master Unit startup checking.
• Initialization of communication with CPU CPU.
• Master Unit I/O configuration initialization after which the Master Unit goes to OPERATE.
• One PROFIBUS DP cycle to request slave diagnostics.
• One PROFIBUS DP cycle to transmit parameter messages to all slave devices.
• One PROFIBUS DP cycle to transmit the I/O configuration messages to all slave devices.
• One PROFIBUS DP cycle to request slave diagnostics.
The average time for the first three actions - assuming a maximum I/O configuration - is approxi-
mately 2 seconds. The remaining time depends on the PROFIBUS settings.
For a maximum I/O configuration, with 125 slave devices, 56 words I/O each, (i.e. the total I/O size
amounts up to 7000 words) one PROFIBUS DP cycle lasts approximately 70 ms. A complete start
up cycle will then last approximately 280 ms.
The total system start up time, from Unit reset until I/O data exchange, will then be 2.3 seconds.
Additional Information
• The NJ-series Controller CPU requires 10 to 20 seconds to start.
• It is recommended to program fail-safe circuits or use effective flags.
5-40
+ 2*T + T
PB,Cyc M,Proc M,Rrf
CJ-series PROFIBUS Master Unit Operation Manual for NJ-series CPU Unit (W509)
+ T + T + T
CPU,Cyc CPU,Rf OUT