Lakeshore Learning Materials 647 - Manual (Page 67)

Lake Shore Model 647 Magnet Power Supply User’s Manual
Mainframe Remote Operation B-1
APPENDIX B
MAINFRAME CONTROL BUS OPERATION
B1.0 GENERAL
There are seven elements to the Model 647 Mainframe Control Bus operating instructions: Control Bus Serial
Interface Specifications (Paragraph B2.0), Control Bus Serial Interface Connector (Paragraph B3.0), Control
Bus Serial Interface Configuration (Paragraph B4.0), Selecting the Control Bus Serial Interface Address
(Paragraph B5.0), Control Bus Serial Interface Operation (Paragraph B6.0), and a sample control bus serial
interface program (Paragraph B7.0).
B2.0 CONTROL BUS SERIAL INTERFACE SPECIFICATIONS
The MPS Mainframe control bus
serial interface may be configured
either for RS-232C or RS-485. RS-
232C is an unbalanced (single
ended), non terminated line for short
distances (typically less than 50 feet)
where the host computer serial
interface is dedicated to one MPS
Mainframe. RS-485 is a balanced,
terminated line for multidrop (party-
line) configurations with up to 32
drivers and receivers sharing the
same line for data transmission. Each
interface instrument has a unique
address and operates in a polled
mode. Set the MPS Mainframe to
respond to one of 32 addresses.
B3.0 CONTROL BUS SERIAL
INTERFACE CONNECTOR
The serial interface connectors use dual standard 6-
wire RJ-11 modular (phone) jacks. The two
connectors are in parallel and facilitate the RS-485
multidrop configuration. Lake Shore Model 2001 data
cables, which maintain pin 1 polarity, simplify
multiple Mainframe interconnection. Lake Shore
offers the Model 2002 RJ-11 to DB-25 adapter and
Model 2003 RJ-11 to DE-9 adapter to connect to the
host computer.
Serial Interface
Specification
Configured
For RS-232C
Configured
For RS-485
Transmission Three Wire Two Wire
Address Configuration None Polled 1-32
Distance 50 Feet 4000 Feet
Connector Dual RJ-11 Modular (phone) Jacks
Timing Format Asynchronous
Transmission Rate Half Duplex
Baud Rate 9600
Bits per Character 1 Start, 7 Data, 1 Parity, 1 Stop
Parity Type Odd
Data Interface Levels Tx/Rx Using EIA Levels
Terminator LF (0AH)
Pin RS-232C Function RS-485 Function
1 No Connection No Connection
2 Receive Data A
3 Signal Ground No Connection
4 Signal Ground No Connection
5 Transmit Data B
6 No Connection No Connection