Lakeshore Learning Materials 647 User Manual

Page 68

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Lake Shore Model 647 Magnet Power Supply User’s Manual

Mainframe Remote Operation

B-2

B4.0 CONTROL BUS SERIAL INTERFACE CONFIGURATION
Configure the control bus serial interface for either RS-232C or RS-485 communications with DIP switches on

the Communications Processor Board (CMP). The CMP plugs into the Mainframe rear panel. The standard

control bus serial interface configuration is RS-485. Use the procedure below to change or verify the serial

interface configuration.

1. Turn off the Mainframe and unplug the power cord.

2. Loosen the two screws that secure the CMP to the rear panel and slide the CMP out.

3. Locate and configure the control bus serial

interface DIP switches as defined in the table

to the right. The DIP switches are just inside

the CMP front panel. Switches 1-4 define the

interface as RS-232C. Switches 5-8 define the

interface as RS-485 multidrop. Switch 8

activates 100 Ω bus termination for long serial

interface runs. For RS-485, terminate

extremely long main lines at the furthest point

from the host. Limit main line length to under

4000 feet and multiple short stub lines from

the main line (Mainframe to Mainframe) to

under 50 feet. A typical RS-485 configuration

runs the main line from the host to one of the

first Mainframe serial interface jacks; a Lake Shore 2001 cable plugs into the other first Mainframe serial

interface jack to connect to the second Mainframe, and so on. Connect up to 32 Mainframes in this way.

Terminate the last Mainframe only if it is a significant distance from the host. Assign unique addresses to

multiple Mainframes on a RS-485 interface.

4. Replace the CMP.

B5.0 SELECTING THE CONTROL BUS SERIAL INTERFACE ADDRESS
Multiple Mainframes on the RS-485 interface each

have a unique address and operate in a polled mode.

Set the MPS Mainframe to respond to one of 32

addresses. Prefix all commands sent to a Mainframe

with the Mainframe address. A Mainframe query

response includes the address prefix if the address is

not 0. The receipt of the LF (0AH) terminator

resynchronizes communications and alerts all Mainframes that the next character is an address. A Mainframe

with address 0 responds to all commands on the interface. A Mainframe using RS-232C can be given a

unique address as well, but RS-232C is not suited for multi-drop operation. Access the Control Bus serial

interface address from the Interface Setup screen. Press the Function Menu key to display Function Menu 1.

Press the key corresponding to INTERFACE SETUP to display the Interface Setup screen.

CB ADD: 0 to 32

Control Bus Address. Use the cursor key to move to the line indicating CB ADD. Use the Up or down Numeric
Entry keys to increment or decrement the Control Bus Address. The initial condition is 0. Range is 0 to 32.

CMP

Configuration

DIP Switch

RS-232C Terminated

RS-485

Unterminated

RS-485

1

Closed

Open Open

2 Closed

Open Open

3 Closed

Open Open

4 Closed

Open Open

5 Open

Closed

Closed

6 Open

Closed

Closed

7 Open

Closed

Closed

8 Open

Closed

Open

S E T U P :

¤ IE E E / S O I

C B D E F

C B A D D

V W A N G L E

M F ID

IM A X S E T

V M A X S E T

O U T P U T :

:

: 9 6 0 0 ,0 ,7 ,1

: 0

: 5

: 6 4 7 (1)

: + 7 2 .0 0 A

: + 3 2 .0 0 V

¥

¥

¥

*

- 0 .0 0 A

+ 0 .0 0 V

L O C

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