GP485A TDK Corporation, GP485A Datasheet - Page 19

• Manufacturer Part Number: GP485A
• Description: GPIB CONTROLLER
• Manufacturer: TDK Corporation
• Series: ZUPr

Specifications of GP485A

• Accessory Type: Controller
• For Use With/related Products: ZUP Series
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: Q4846340

4.9
The IEEE 488 specification defines two ways that GPIB Talkers and Listeners can identify the last byte
of data messages: END and EOS. The two methods permit a Talker to send data massages of any
length without the Listener(s) knowing the number of transmission bytes in advance. END and EOS
can be used individually or in combination, but the Listener must be configured to detect the end of
transmission.
END message:
transmitted. The Listener stops reading when it detects a data byte accompanied by
of the value of the byte.
EOS character:
The Listener stops receiving data when it detects the EOS character. Either a 7-bit ASCII character or a
full 8-bit binary byte can be used.
When the GP485 receives it’s own talk or listen address, no EOS modes are in effect. When talking, the
GP485 asserts
address, the EOS modes in effect are those that the user selects using the
Table 4-4: Serial port response byte
4.10 SERIAL PORT TRANSMISSION
4.11 OPERATION OF THE GP485 AS A GPIB DEVICE
4.12 SERIAL POLL RESPONSES
The GP485 checks the data received from the serial device for errors while it buffers data. If a serial port
error occurs, The GP485 records the appropriate error code. There are two ways to determine if a serial
port error has occurred:
* Use the
* Serial poll the GP485 and check the serial poll response byte to see if it’s SERR bit is set. Refer to Par.
Program the GP485 to ignore serial port errors using the
The GP485 operates like any other GPIB device and, as such, is configured to respond in certain ways
to GPIB commands.
When serial polled, the GP485 returns status information to the GPIB controller through the serial poll
response byte. The GP485 maintains this status byte throughout operation, regardless of the
configuration. Table 4-4 lists the meaning of each bit in the serial poll response byte.
Bit Mnemonic Meaning
0
1
2
3
4
5
6
7
reported, it is automatically cleared and no further action to the GP485 is necessary.
4.12 later in this chapter.
-
BF
GERR
SERR
BNE
EOS
RQS
-
(END and EOS)
GPIB READ AND WRITE TERMINATION METHODS
st
at function to request the GP485 status information. After the serial error code has been
EOI
The Talker asserts the
The Talker transmits an EOS (end-of-string) character at the end of it’s data string.
Not used
Serial port receive buffer is full and serial device not addressed to talk.
GPIB error - see
Serial error - see
Serial port receive buffer not empty and serial device not addressed to talk.
EOS character received and serial device not addressed to talk.
Request service (
Not used
*
with the last byte of it’s response. When the GP485 receives the serial device talk
st
st
SRQ*
at Table 5-5
at Table 5-5
EOI
asserted)
*
(End or Identify) signal while the last data byte is being
spi
gn function.
eos
function.
EOI
*
, regardless
srq
en