ARJAY ENGINEERING EC-Gold Dual Bedienungsanleitung PDF herunterladen (Seite 16)

Model: PG-2000

pg2000capum45.DOC Rev: 4.5

- 14 -

5.0 BMCS ACCESS

The Enmet CAP's (Central Access Panels or Scanners) may be accessed via an RS-485 link using the

Modbus protocol. Up to 28 CAP units may be connected on a single network – in this case only 2 are

connected.

The BMCS acts as a Modbus master.

5.1 SETUP

Each CAP unit must be given a unique Address so it can be specifically be accessed by the BMCS. This

is done as follows:

• Press the Setup key on the CAP keypad.

• Press 3 for Cap Configuration.

• Press 3 for CAP Net Address.

• Enter the desired Address. This value is typically already set at the factory starting at 1 and

increasing incrementally for additional CAP units in the system.

5.2 SERIAL CONFIGURATION

2 Wire RS-485 (1/2 Duplex)

9600 Baud, Even parity, 8 Data bits, 1 stop bit.

For connection to a PC, an RS-485 to RS-232 converter module may be used. This module plugs into

the PC’s serial port and provides a 2 wire RS-485 connection. For convenience, a port-powered

converter should be used.

The following RS-485-232 converter has been tested with the system:

Model: 485SD9TB (Manufacturer: B&B Electronics )

5.3 MODBUS ACCESS REGISTERS

The Enmet CAP is a Read Only device i.e. the BMCS can only read, but not modify information in the

CAP.

5.3.1 MODBUS COMMANDS SUPPORTED

Read Holding Registers (Modbus command # 3)

Other modbus commands are NOT supported.

5.3.2 REGISTER MAP

The main information intended for the BMCS is the highest ppm concentration read

by the CAP from any EC Gold transmitters networked to it. This information is used

by the BMCS to control the ventilation fan speed.

This MAX PPM value is in IEEE754 format, which is 4 bytes or 2 consecutive

modbus registers. The packing is as follows:

Floating point value (before transmission):

Byte 3 (Most Sig. Byte) Byte 2 Byte 1 Byte 0 (Least Sig. Byte)

As Sent: (First to last): Byte 1, Byte 0, Byte 3, Byte 2.

i.e. Byte 1 is sent first followed by Byte 0, then Byte 3 and finally Byte 2.

If 2

second serial port is purchased, see attached “Scanner Modbus MAP”

1 2 ... 11 12 13 14 15 16 17 18 19 20 21 22

Keine Kommentare

ARJAY ENGINEERING EC-Gold Dual Bedienungsanleitung Seite 16