Table of Contents
Advertisement
PRODUCT DESCRIPTION
INTRODUCTION
The LeCroy Model 2132 is a single-width CAMAC module used to allow
bi-directional communication between the CAMAC Dataway and the
System 1440 or HV4032 or HV4032A mainframes. Please note however,
that the 2132 should be used with the 1440 system or the HV4032
system. It cannot be used with both systems at once. Any combination of
the HV4032 series mainframe may be used in the daisy chain. The
system employs a five pair 20 mA current loop serial bus. Data are
transmitted at 2400 BAUD using a modified ASCII code. Sixteen bit data
words are transmitted as three bytes, each with its own parity bit. Checks
for data transmission errors (parity) are accommodated by firmware at
the addressed high voltage chassis or by hardware at the 2132.
The bus consists of two serial data pairs, two bus priority pairs and one
pair to differentiate between CAMAC and TTY operation. A cable of up to
1000 feet maybe reliably employed between the 2132 and the first HV
chassis. Up to 100 feet between chassis' may also be employed.
Using the 2132, all front panel operations can be performed remotely
(high voltage hardware limit and HV gate are excluded). Commands are
available to turn on, turn off, set and read voltage of any one channel or
all channels in any one HV mainframe.
Because CAMAC is so much faster than the serial bus, 40 word memo-
ries are employed to buffer both the R and W lines. This allows the user
to initiate a read only after all data are transferred, thus minimizing the
dead time of the attendant computer. Completion of a routine data
transfer to the 2132 sets a low priority LAM (L2) (HV4032A only). Error
signaling uses a high priority LAM (L1). These LAMs may be detected by
CAMAC Look-at-Me and identified through the CAMAC Read (R1 = L1,
R2 = L2). A front-panel ERROR output is clamped to ground (open
collector 300 mA sink) when any mainframe reports an error via the
serial bus allowing the user to trigger an external alarm.
The response time of the HV mainframes depends upon the specific
command issued. "Read One Voltage" commands require only a few
msec in contrast with "Turn HV On", which requires approximately 20
seconds. For this reason, a Finished Response is returned after HV4032
has accomplished the task. Although this response can be disabled, it is
strongly recommended that this feature be used
Communications between the CAMAC 2132 and the HV4032 main-
frames are of several types. All communication from the 2132 to the
HV4032 will be called COMMANDS, and all communication from the HV
mainframes to the 2132 will be called RESPONSES. The HV mainframes
will spontaneously respond to indicate a failed channel. Otherwise, the
HV mainframes will respond only after receipt of a COMMAND from the
2132.
Conversely, most valid COMMANDS from the 2132 will be acknowledged
by a RESPONSE from the addressed mainframe. Those commands
having a defined response are called HANDSHAKE COMMANDS. These
are outlined in Figure 1.
Any non-handshake command can generate a Finished response (user's
option) for convenience of operation.
7
Advertisement
Table of Contents
