Alicat EPCD Series Manuel d'utilisation - Page 8

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Streaming Mode (RS-485 units do not have streaming mode)

In Streaming Mode, a device will automatically output the data stream at a pre-

determined rate. The default rate is set to 50 ms. Only one unit on a given COM

port may be in streaming mode at a time.

To change a unit from Polling Mode to Streaming Mode, type (unit

ID)@=@<CR>. This is equivalent to changing the unit ID to "@". If data does

not appear, check all the connections and COM port settings.

When sending a command to a unit in streaming mode, the flow of information

will not stop while the user is typing; and the typed text may not be readable

depending on the terminal settings. If the unit does not receive a valid

command, it will ignore it. If in doubt, simply perform another carriage return

and start again.

To change a unit from Streaming Mode to Polling Mode, type @@=(unit

ID)<CR>. If entered correctly, the data stream will stop and the device will

now be in polling mode.

Data Format

The data frame on the screen represents the current measurements in the

device in the units shown on the display. By default, pressure controllers are

configured to output three columns of data

All data is displayed in the "device units" selected on the unit. Devices come

standard with units of PSIA or PSIG, depending on the type of the device.

The first column is the unit ID. This column will be excluded if the device is in

streaming mode. The next column is pressure, and the third column will display

setpoint.

For example, suppose a controller with unit ID A was ordered with units of inHgG

and currently has a setpoint value set to 50.42 inHgG. The data frame may read:

EPC/EPCD-Series Pressure Controller Data Format

Additional columns, including status codes, may be present to the right of the

last column.

Sending a Setpoint via RS-232 / RS-485

EPC's can be ordered in analog input mode or in RS-232/RS-485 input mode. If

you've ordered the EPC in RS-232/R-S485 input mode the following section will

provide instructions on sending a setpoint via RS-232/RS-485.

If you've ordered the EPC in analog input mode and wish to change over to

RS-232/RS-485 input mode, you must read and adjust register 20 in the 16

bit programming of your EPC. Please contact the factory for instructions

on changing from Analog to RS-232/RS-485 input mode via RS-232/RS-485

adjustment.

To send a setpoint via RS-232 / RS-485:

Method 1: Setpoint may be set as a floating point number in serial

communication using the setpoint command (unit ID)S(floating

point number)<CR>. For example, AS4.54<CR> changes the setpoint for

unit "A" to 4.54 in the current device units.

Method 2: The setpoint can also be set in reference to a portion of the full

scale. Type (unit ID)(integer)<CR>. Values between 0 and 64000 are

acceptable, which correspond linearly to 0 and 100% full scale flow respectively.

Once a setpoint is accepted, the data frame will be returned with the setpoint

column changed accordingly.

Unit ID

+50.42

Pressure

50.42

Setpoint