42
mode, Operate or Standby state, instructed to calculate the required current, start energy timing of
events countdown and controlled for positive or negative power (optional). New energy data or event
count, power, power factor, frequency and deviation range can be transmitted to the Series 800 while
the calibrator is in either the Operate or Standby state. Voltage information can only be transmitted
while the calibrator is in the Standby state. During the energy timing or event countdown no new
command will be acted upon. To abort this mode a Select Device Clear command must be received
by the calibrator. The Series 800 asserts the service request status bit whenever one or more of the
status functions is asserted. The controller can then conduct a serial poll and will receive the
complete status byte from the Series 800. The Series 800 can also transmit data, either deviation or
energy delivered. All communications are handled in standard ASCII format.
5.2 Data Entry
The following steps describe the procedure by which instructions are sent to the Series 800 via the
IEEE-488 Interface.
1. Data is entered by a two byte instruction plus a two byte field instruction (in most instances).
• Alpha: F, S, T, U, V, W, A or B, C, P or L, and H.
• Numerical values.
2. Typical data entry:
• "F0S1T2U0" = 120 volts. (F0 means that the following alpha and numerics represent the
voltage amplitude)
• "F5S1T0U0V0W0" = 10000 Watts. (F5 means that the following alphas and numerics
represent the Volt-Ampere value)
• "F6S1T0U0V0W0" = 10000 VA-seconds or counts. (F6 means that the following alphas and
numerics represent the VA or KVA- seconds or Event Count values, 811A only.)
• "P5L1" = +.5 PF.
3. Alpha bytes must always precede numerics and both the alpha and numeric characters must
always be sent.
4. The command message sent must be terminated by a Carriage Return (CR)/Line Feed (LF) or
EOI.
5. Data may be entered in any order; values not entered always retain the last assigned value.
6. It is always a smart practice to transmit the complete command string every time. This can be
easily done by assembling the word into a literal variable (string) and outputting this string each
time.
5.3 Serial Poll Code
The following steps describe the procedure by which the Series 800 may be serial polled to read the
status byte from the Series 800 via the IEEE-488 Interface. Refer to Table 5-2.
1. Excitation applied is a timed signal occurring after the output relays, K6, K6A and K8 are
activated and the squelch has been removed.
To Next Page
Loading...