Emerson Vilter Vission 20/20 Operation And Service Manual Download

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C - 27

Appendix C

•

Remote Control and Monitoring of Vission 20/20 Panel

Vission 20/20 • Operation and Service Manual • Emerson • 35391SC 2.7

NOTE

Both Process Temp Control and Suction Pressure

Control must be enabled from the Configuration

screen to do this.

Modbus Register 40503 - Auto Capacity Control

Type

0 = Suction Pressure (if enabled from Configuration

screen)

1 = Process Temp (if enabled from Configuration

screen)

2 = Discharge Pressure (if enabled from Configuration

screen)

Compressor Start and Stop Commands
Modbus Register 40508 - Start Command

1 = Start Compressor in Remote Auto Mode
2 = Start Compressor in Auto Sequencing Mode

Four (4) minute Remote mode time-out timer
• Once the compressor has been started in Remote

Auto Mode using the Start Compressor Command, a
4 minute timer will start. If no further communica-
tion takes place to the 20/20 within 4 minutes, the
20/20 will be placed in Local Auto mode, a yellow
banner will be displayed on the 20/20 signifying that
a “Remote Comm Time-out” occurred, and the Event
List will get populated with a time-stamped “Remote
Comm Time-out” event.

Modbus Register 40509 - Stop Command

1 = Stop Compressor Command
• Vission 20/20 panel will remain in Remote (Idle)

mode after a Stop Compressor command has been
issued.

Remote Control via Direct I/O (Hard-wired)

Remote Control of the compressor can also be accom-
plished using hard-wired inputs. These include Remote
Start-Stop digital input, Remote Increase Capacity digi-
tal input, Remote Decrease Capacity digital input, and
Remote Caphold Setpoint analog input. For communi-
cation register information, refer to Table D-1.

Configuration Screen Setup:

(Reference the “Communication” section of Figure C-14)

For Direct I/O control:
•

Configure the “Active Remote Control” drop-down

box to “Direct I/O”. This selection activates the
Remote Start-Stop digital input. This is the ONLY se-
lection that activates the Remote Start-Stop digital
input.

• Below the “Active Remote Control” selection box,

check the “Direct I/O”” box.

A popup “Direct I/O Control Type” box now appears,
from which you can select the desired control method:

•  Auto Capacity
•  (Digital) Manual Capacity – comp. capac-
ity controlled via digital increase and decrease
inputs.
•  (4-20mA) Capacity Hold – compressor capac-
ity controlled via Remote Caphold analog input.

Auto Capacity
• The compressor is started and stopped from the

Remote Start/Stop input, but the compressor capac-
ity is controlled from the internal compressor control
setpoints entered in the 20/20. The Auto-cycle set-
points can be enabled or disabled as desired.

(Digital) Manual Capacity
• The compressor started and stopped from the

Remote Start/Stop input, but the compressor capac-
ity is controlled from the Remote Capacity Increase
and Remote Capacity Decrease digital inputs.

(4-20mA) Capacity Hold
• The compressor started and stopped from the

Remote Start/Stop input, but the compressor capac-
ity is controlled from a 4-20mA analog signal run to
20/20. The 4-20ma signal will be proportional to
0-100% capacity hold value. For instance, 4mA = 0
percent, 12mA = 50%, and 20mA = 100%.

Hold Capacity Operation
•

The Capacity Hold analog signal defines a “target”

capacity slide valve position for the compressor. The
20/20 will position the capacity slide to the “target”
position. rules of this capacity hold algorithm are;

1. If the new target is < 0.4% (full scale) away from the

current position – then don’t do anything – this is the