Power-on sequencing (some models)

You can use the power-on sequence function to define a sequence for powering on the PDU outlets. You can use Telnet and SNMP through the Ethernet port or HyperTerminal through the serial port to configure the power-on sequence function.

About this task

Use the power-on sequence function for the following two scenarios:
  • Device dependency There are applications that required the power-on sequence function. For example, a system includes device A, device B, and device C and requires that device A is powered on first, then device B, and then device C. If the devices do not follow the required sequence when powered on, the system will not run correctly.
  • Power-on in-rush current In-rush current might be a problem in some applications if you are powering on multiple devices at the same time. In such applications, the power-on sequence function is required to power on devices in user-definable sequences to limit in-rush current.
To use the power-on sequence function, you must set the following parameters by using either a serial or Ethernet interface:
  • GlobalDelayTimer (range: from 0 - 3600 seconds; data type: integer). All PDU outlets are controlled by this global timer.

    If GlobalDelayTimer is not set (equal to 0), the global delay function for all outlets is not enabled.

  • IndividualDelayTimer (range: from 0 - 3600 seconds; data type: integer). Each outlet also has its own individual delay variable (IndividualDelayTimer) that is accessible through either a serial (HyperTerminal) or Ethernet (Telnet and SNMP) interface.

    If IndividualDelayTimer is not set (equal to 0), the individual outlet delay function is not enabled.

If both the GlobalDelayTimer and IndividualDelayTimer parameters are not set, the power-on sequence function is off automatically.

When a PDU is powered on for the first time, all the relays are off, and the power-on sequencing is not used. You must turn on the relays by using the web interface or SNMP. You must also set the values for the GlobalDelayTimer and IndividualDelayTimer, if they are used. After that, when the PDU is turned on (or power is restored), the outlet power-on sequence and behavior are controlled by the following settings:
  • Previous state of the outlets (on or off)
  • GlobalDelayTimer value
  • IndividualDelayTimer value

The outlets that were off before the PDU was turned off (or lost power) will stay off after power is restored.

The outlets that were on before the PDU was turned off (or lost power) will be tuned back on in a sequence that is determined by the timers. If the timer values are zero, the only delay is the PDU boot-up time, which is 10 seconds. If there are values in the delay timers, the turn on time is the sum of following three values:
  • PDU boot-up time (10 seconds)
  • GlobalDelayTimer value
  • IndividualDelayTimer value
The following example shows what you can expect to see if power to the PDU is restored after a power outage.
  • PDU boot-up time = 10 seconds
  • GlobalDelayTimer = 5 seconds
  • The previous outlet state for the PDU is:
    Outlet 1 On
    Outlet 2 On
    Outlet 3 On
    Outlet 4 Off
    Outlet 5 On
    Outlet 6 On
    Outlet 7 On
    Outlet 8 On
    Outlet 9 On
    Outlet 10 Off
    Outlet 11 On
    Outlet 12 Off
  • The IndividualDelayTimer for each outlet has the following settings:

    Outlet 1 1 Sec
    Outlet 2 2 Sec
    Outlet 3 3 Sec
    Outlet 4 5 Sec
    Outlet 5 2 Sec
    Outlet 6 2 Sec
    Outlet 7 4 Sec
    Outlet 8 1 Sec
    Outlet 9 2 Sec
    Outlet 10 2 Sec
    Outlet 11 5 Sec
    Outlet 12 3 Sec

The following table shows the PDU outlet power-on timing when power is restored after a power outage.
Table 1. Power-on timing
Outlet number Outlet power-on timing Comment
1 16th second Total Delay time = bootup time + GlobalDelayTimer + IndividualDelayTimer
2 17th second Total Delay time = bootup time + GlobalDelayTimer + IndividualDelayTimer
3 18th second Total Delay time = bootup time + GlobalDelayTimer + IndividualDelayTimer
4 Off Previous state is Off
5 17th second Total Delay time = bootup time + GlobalDelayTimer + IndividualDelayTimer
6 17th second Total Delay time = bootup time + GlobalDelayTimer + IndividualDelayTimer
7 19th second Total Delay time = bootup time + GlobalDelayTimer + IndividualDelayTimer
8 16th second Total Delay time = bootup time + GlobalDelayTimer + IndividualDelayTimer
9 17th second Total Delay time = bootup time + GlobalDelayTimer + IndividualDelayTimer
10 Off Previous state is Off
11 20th second Total Delay time = bootup time + GlobalDelayTimer + IndividualDelayTimer
12 Off Previous state is Off

The following sections explain how to configure the GlobalDelayTimer and IndividualDelayTimer parameters through the serial port (by using HyperTerminal or similar applications) or through the Ethernet port (by using Telnet and SNMP).