Lakeshore 325, Руководство пользователя, Страница: 88 / 166

Lake Shore Model 325 Temperature Controller User’s Manual
6-2 Remote Operation
Changing IEEE-488 Interface Parameters (Continued)
Press the
s
or
t
keys to increment or decrement the IEEE address to the desired number. Valid addresses are 1 through
30. Default is 12. Press Enter to accept new number or Escape to retain the existing number. Pressing Enter displays
the Terminators screen.
Select-With-°®
IEEE Term--Cr-Lf
Press the
s
or
t
keys to cycle through the following terminator choices: CR/LF, LF/CR, LF, and EOI. The default is
Cr Lf. To accept changes or the currently displayed setting, push Enter . To cancel changes, push Escape .
6.1.2 Remote/Local Operation
Normal operations from the keypad are referred to as ‘local’ operations. The Model 325 can also be configured for
‘remote’ operations via the IEEE-488 interface or the
Local key. The Local key will toggle between remote and local
operation. During remote operations, the remote annunciator “R” will be displayed in the top right of the OLED display,
and operations from the keypad will be disabled.
6.1.3 IEEE-488 Command Structure
The Model 325 supports several command types. These commands are divided into three groups.
1. Bus Control – Refer to Section 6.1.3.1.
a. Universal
(1) Uniline
(2) Multiline
b. Addressed Bus Control
2. Common – Refer to Section 6.1.3.2.
3. Device Specific – Refer to Section 6.1.3.3.
4. Message Strings – Refer to Section 6.1.3.4.
6.1.3.1 Bus Control Commands
A universal command addresses all devices on the bus. Universal commands include uniline and multiline commands. A
uniline command (message) asserts only a single signal line. The Model 325 recognizes two of these messages from the
BUS CONTROLLER:
Remote (REN) and Interface Clear (IFC) . The Model 325 sends one uniline command: Service
Request (SRQ) .
REN (Remote) – Puts the Model 325 into remote mode.
IFC (Interface Clear) – Stops current operation on the bus.
SRQ (Service Request) – Tells the bus controller that the Model 325 needs interface service.
A multiline command asserts a group of signal lines. All devices equipped to implement such commands do so
simultaneously upon command transmission. These commands transmit with the Attention (ATN) line asserted low.
The Model 325 recognizes two multiline commands:
LLO (Local Lockout ) – Prevents the use of instrument front panel controls.
DCL (Device Clear) – Clears Model 325 interface activity and puts it into a bus idle state.
Finally, addressed bus control commands are multiline commands that must include the Model 325 listen address before
the instrument responds. Only the addressed device responds to these commands. The Model 325 recognizes three of the
addressed bus control commands:
SDC (Selective Device Clear) – The SDC command performs essentially the same function as the DCL command,
except that only the addressed device responds.
GTL (Go To Local) – The GTL command is used to remove instruments from the remote mode. With some
instruments, GTL also unlocks front panel controls if they were previously locked out with the LLO command.
SPE (Serial Poll Enable) and SPD (Serial Poll Disable) – Serial polling accesses the Service Request Status Byte
Register. This status register contains important operational information from the unit requesting service. The SPD
command ends the polling sequence.