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javihnrqz · Junior Joined: 13 Dec 2018 Posts: 4

Hi guys, I have a question regarding a ControlLogix PLC.
It happens that according to the drawings I might have two modules connected on the ControlLogix: a 1756-ENET/B and a 1756-CNB/D. What happens is that I only have one module that is the 1756-CNB/D that provides me ControlNet interface to the loop made by PowerFlex 70 drives. I see that the 1756-CNB/D has a Ethernet input, so my question is:

¿Do I need a 1756-ENET/B if I have the 1756-CNB/D?

Is it like built-in the Ethernet capability or how does it work?

Thanks in advance people.

Javier Henríquez.

capo_di_tutti_capi · Junior Joined: 17 Nov 2017 Posts: 10

http://apps.watersurplus.com/techlib/Allen%20Bradley/AB_PowerFlexControlNetAdapter_20COMMC_user_D1101.pdf

PowerFlex 70/700: Typical PI Loop Configuration

Question
What is a typical PI loop configuration for PowerFlex 70/700 drives?

Environment
20A PowerFlex 70
20B PowerFlex 700
Answer
A typical PI loop configuration for PowerFlex 70/700 drives is described below:

Note: For PowerFlex 70 and 700 standard control drives only (not enhanced or vector control) set Parameter 80 [Speed Mode] to a value of 2 "Process PI".

Set Parameter 90 [Speed Ref A Sel] to a value of any true master speed reference such as an unused analog input or DPI port.

Set Parameter 124 [PI Configuration] bit 4 "Zero Clamp" = 1 . This will prevent the drive and motor from running in the reverse direction.

Set Parameter 124 [PI Configuration] bit 0 "Excl Mode" = 1. This exclusive mode forces the drive to receive its speed reference, acceleration, and deceleration rates from the PI loop.

Optional: Parameter 124 [PI Configuration] bit 1 "Invert Error" can be set to a value of 1 if the process requires it. For example, if the feedback is a temperature device that increases with temperature the fan will have to increase to decrease the temperature back to the setpoint. This type of inverse relationship requires this bit to be set or the PI output will increase when it should decrease and vice-versa.

Optional: To enable/disable the PI Loop:

Parameter 125 [PI Control] bit 0 "Enable PI" can be set to a value of 1 to enable or 0 to disable the PI Loop.

Set a digital input such as Parameter 364 [Digital In4 Sel] = 26 [PI Enable] to enable and disable the PI Loop through a digital input terminal. Note: In this case Parameter 125 [PI Control] bit 0 "Enable PI" must still be set to 1, and the digital input must have voltage applied in order to enable the PI loop.

Set Parameter 126 [PI Reference Sel] to a value of 0 "PI Setpoint" (default).

Set Parameter 127 [PI Setpoint] to a value of 50% (default).

Set Parameter 128 [PI Feedback Sel] to a value of 1 "Analog In 1" or 2 "Analog In 2".

Set Parameter 131 [PI Lower Limit] so that the value is equal to Parameter 55 [Maximum Frequency] for standard control PowerFlex 70/700 or a value of -100% for the PowerFlex 70/700 Enhanced/Vector Control.

Set Parameter 132 [PI Upper Limit] so that the value is equal to Parameter 55 [Maximum Frequency] for standard control PowerFlex 70/700 or otherwise a value of +100% for the PowerFlex 70/700 Enhanced/Vector Control.

AIX · Junior Joined: 06 Sep 2017 Posts: 9

RJ-45 on 1756-CNB isn't Ethernet, this is Network Access Port for connecting various clients, like PC, to ControlNet network with 1784-KTC, -KTCx,
or -PCC communication card and a 1786-CP cable.
If you want communicate with PLC from Ethernet network, you need 1756-ENxx module.