Accessing I/O Channels - HP E1419A User Manual

Accessing I/O
Channels
114 The Algorithm Language and Environment
In the Algorithm Language, channels are referenced as pre-defined variable
identifiers. The general channel identifier syntax is "Iccc" for input channels
and "Occc" for output channels; where ccc is a channel number from 100
(channel 0) through 163 (channel 63). Like all HP E1419A variables,
channel identifier variables always contain 32-bit floating point values even
when the channel is part of a digital I/O SCP. If the digital I/O SCP has 8-bit
channels (like the HP E1533), the channel's identifiers (Occc and Iccc) can
take on the values 0 through 255. To access individual bit values you may
append ".Bn" to the normal channel syntax; where n is the bit number (0
through 7). If the Digital I/O SCP has single-bit channels (like the
HP E1534), its channel identifiers can only take on the values 0 and 1.
Examples:
O148 = 1;
Inp_val = I160;
Bit_4 = I156.B4;
Output Channels
Output channels can appear on either or both sides of an assignment
operator. They can appear anywhere other variables can appear. Examples:
O132= 12.5;
O156.B4 = ! O156.B4;
writecvt(O132,32);
Input Channels
Input channel identifiers can only appear on the right side of assignment
operators. It doesn't make sense to output values to an input channel. Other
than that, they can appear anywhere other variables can appear. Examples:
dig_bit_value = I157.B0;
inp_value = I124;
O132 = 4 * I124;
writefifo(I124);
assign value to output chan 0 on
HP E1534.
from 8-bit channel on HP E1533
Inp_val will be 0. to 255.
assign HP E1533 chan 56 bit 4
to variable Bit_4
send value to output channel
buffer element 0
compliment value found in output
channel buffer element 56, bit 4
each time algorithm is executed.
send value of output channel 132
to CVT element 32
retrieve value from Input
Channel Buffer element 57, bit 0
retrieve value from Input
Channel Buffer element 24
retrieve value from Input
Channel Buffer element 24,
multiply by 4 and send result to
Output Channel Buffer element
32
send value of input channel 24 to
FIFO buffer
Chapter 4