Tektronix Keithley PIM1 Pulse,Frequency Input Module Rev. C User manual

PIMI

Pulse and Frequency Input Module

The PIMl Pulse and Frequency Input Module provides eight frequency or event counter
inputs. Eight software-controlled ranges allow frequency measurements up to a maxi­mum of 8MHz and down to a resolution of lHz. Seven of the inputs provide isolated
(to 400V) or non-isolated TTLcompatible inputs, while an eighth channel has a non­isolated sensitivity of 200mV.

As a frequency counter, the seven TTLcompatibIe inputs provide measurements to
8MHz in the non-isolated mode, and to 2MHz in the isolated mode. The eighth input,
which has 200mV sensitivity, measures frequencies up to lMHz, non-isolated only.

As an event counter, the PlMl module can count pulses at a maximum rate of 25OkHz.
Anti-coincidence circuitry ensures that the counter is not read in an undefined state
and that no pukes will be lost. Inputs may also be configured as four dual input chan­nels to allow events to be gated by external sources.

Software control selects input channel, input gating, gate times, and frequencylevent
mode. Gate times between 1048.576msec and 8.192msec allow a wide range of frequen­cies to be measured. Signals are connected directly to the module via on-card screw
terminals.

The RIM1 module may be placed in any available slot in the system. To install the
module, remove the baseboard cover and install it with the component side facing the
power supply.

CAUTION: Always turn off the system power before installing or removing modules.
To avoid possible EM1 radiation, never operate the system with the top cover removed.

User-Configured Components

Switches SlOl-X07 independently select isolated or non-isolated inputs for channels 1
through 7 respectively.

All input connections are made to screw terminals on Pl72. Two terminals are provided
for each channel (+ and -). All terminals accept 16-24 gage wire stripped to 3116 of an
inch. See Table 1 and Figure 1 for a list of user-configured components and their loca­tions on the KM1 board.

Document Number: 500-938-01 Rev. C

mm-1

PIMl-2

Figure 1. PM1 Module

Table 1. User-Configured Components on the PIMl

Name Designation Function

Switch 101 sl.01
Switch 102

s102
Switch 103 sl.03
Switch 104
Switch 105
Switch 106
Switch 107

s104

s105

S106

s107
Screw Terminals l?v2

Chan 1 Isolated/Non-isolated Selection
Chan 2 Isolated/Non-isolated Selection
Chan 3 Isolated/Non-isolated Selection
Chan 4 Isolated/Non-isolated Selection
Chan 5 Isolated/Non-isolated Selection
Chan 6 Isolated/Non-isolated Selection
Chan 7 Isolated/Non-isolated Selection
Inout connections, Channels O-7

Connections

Connecting terminals for the PIMl module are shown in Figure 2 which illustrates a
typical connecting scheme. Note that connections will be the same whether an isolated
or non-isolated configuration is used. See below for more information on the isolated
and nonisolated modes.

Figure 3 shows a possible connecting scheme for cases in which PIMl module is soft­ware configured to accept gated inputs. For more information on gated inputs see the
discussion of the CONTROL REGISTER command below.

When making any connection to the PIMl, keep in mind that channels l-7 are designed

for TTL compatible inputs, while channel 0 has 200mV sensitivity. Also, the use of
shielded cable is recommended to minimize the possibility of EMI radiation. Connect
one end of the shield to a rear chassis ground post and leave the other end discon­nected. Do not use the shield as a signal-carrying lead.

Figure 2. Typical PM1 Connections

IOOmV MINIMUM (CHANNEL 0)

,; LEVEL (CHANNELS I-7)

PIMl-3

Figure 3. Typical Connections for Gated Mode

Isolated/Non-isolated Input Mode Selection

Channels 1 through 7 of the l?IMl module may be operated in either isolated or non­isolated TTLcompatible modes. Switches SlOl-907 select the input mode for channels
1 through 7 respectively (see Figure 1) When in the isolated mode, the input signals
may be floated up to 400V above chassis ground. Note that the maximum frequency
that can be measured is reduced to 2MHz when an input channel is used in the
isolated mode, regardless of the selected frequency range.

When an input channel is configured as an isolated input, the minimum input current
for rated frequency is 6.5mA, and the maximum input current is l5mA. The driving

device can be configured to either source or sink the input current. Typically the device
sinks current, as shown in Figure 4. With this configuration, the maximum value of V
is 8.7V. For higher voltages, a resistor can be inserted in series between the supply
voltage and the + terminal. Compute the value of this resistor with the following
formula:

V-l .7

R=-

0.01

-330

PIM1-4

Note that this value will result in a nominal current of about lOmA.

For example, assume that a supply of 24V is used for V+. The resistor value is then
computed as follows: