KEPCO TMA 4882-27 - Manual (Page 28)

3-2
TMA 4882-27 021910
(Refer to Table 2-4 for input/output signal allocations.) The commands then program the
selected Kepco power supply via a serial control bus.
3.4 IEEE 488 (GPIB) BUS PROTOCOL
Table 3-1 defines the interface capabilities of the TMA 4882-27 controller (Talker/Listener) rela-
tive to the IEEE 488 (GPIB) bus (reference document ANSI/IEEE Std 488: IEEE Standard Digital
Interface for Programmable Instrumentation) communicating with a Host Computer–Controller
(Talker/Listener).
Tables 3-2 and 3-3 define the messages sent to the TMA 4882-27, or received by the TMA
4882-27, via the IEEE 488 bus in IEEE 488 command mode and IEEE 488 data mode, respec-
tively. These messages are enabled during the “handshake” cycle, with the TMA 4882-27 con-
troller operating as either a Talker or a Listener.
3.4.1 STRING PARSING
When the TMA 4882-27 is in listen mode, strings are accepted. When the host controller sends
the last byte it can assert the EOI line to indicate the string is complete. The GPIB listener func-
tion automatically adds a LF to terminate the string input. The parsing software then processes
the string and if there are valid commands, the power supply is updated with the new control
input. Some GPIB host controllers do not have the ability to assert the EOI control line, however
the GPIB listener function will also terminate the string input when either a carriage return (0d
H
)
or Line Feed (0A
H
) character is received.
TABLE 3-1. IEEE 488 (GPIB) BUS INTERFACE FUNCTIONS
FUNCTION
SUBSET
SYMBOL
COMMENTS
Source Handshake SH1 Complete Capability (Interface can receive multiline messages)
Acceptor Handshake AH1 Complete Capability (Interface can receive multiline messages)
Talker T6
Basic talker, serial poll, unaddress if MLA (My Listen Address) (one-byte
address)
Listener L4 Basic listener, unaddress if MTA (My Talk Address) (one-byte address).
Service Request SR1
Complete Capability. The interface sets the SRQ line true if there is an
enabled service request condition.
Remote/Local RL2 No Local lock-out. (To disable GTL command
Parallel Poll PP0 No Capability
Device Clear DC1
Complete Capability. Controller sends DCL (Device Clear) and SDC
(Selected Device Clear) to selected power supply.
Device Trigger DT1 Complete Capability. Accepts GET command
Controller C0 No Capability