Teledyne powerpod 400 Serial Communication, Commands, Set Point Queries, Alarm/Flag Queries

10.9. SERIAL COMMUNICATION

Follow the instructions in the section, WIRING THE POWERPOD-400for cabling and proper pin out for serial communication with the unit. After insuring that the POWERPOD-400is wired properly, the unit must be set up following the instructions in the section entitled, External Communications Setup.

The instruction set for the POWERPOD-400can be divided into two different types. They differ only in that they

1.Write a command only or

2.Write a command and read a response.

Taking liberty with this vernacular, they may be differentiated using the terms COMMAND or QUERY. The entire set of instructions can be found in Appendix B.

10.9.1. Commands

Typical RS-232 command structure is as follows: CMNDn<value>Cr

For example: To change channel three’s high alarm value to 75.00, send A3H075.00Cr.

RS-485 commands require only that an asterisk and the unit’s address precede the RS-232 Command. Using the same example as above with a unit whose address is 10 (default), send *10A3H075.00Cr.

When the POWERPOD-400is the terminating unit on a 485 bus, two jumpers, CJ1 and CJ2 can be shorted to add the required terminating resistors. Remove two machine screws from the rear of the top cover. Slide the cover off. The two jumpers are near the serial communication connectors.

10.9.2. Set Point Queries

Queries are used when information from the unit is required. Each query is followed by a response from the POWERPOD-400.

In this case, the query is asking for a programmed value. Specifically, the set point of channel three, which happens to be set at 50.00 of 100.00.

Sent	SP3Cr
Response	SP3 050.00

10.9.3. Alarm/Flag Queries

The state of the high and low flow alarms for each channel can be monitored via the DB-15 connecter (J8) on the rear panel for immediate action from an alarm situation but the Totalizer set points can only be monitored by reading a memory location’s Boolean setting via serial communication.

As shown in the section, Setting Limit Alarms, to simply QUERY channel three’s high alarm set point, send A3HCr. Expect a response similar to A3H 075.00. The actual state of the alarm can be polled using the STATUS query.

STCr

Which results in a response similar to

STATUS

OCA : CH1 AUTO CH2 CLOSED CH3 OPEN CH4 AUTO

HI/LO: 0/0 0/1 1/0 0/0

OCA is short for OPEN/CLOSED/AUTO.

HI/LO stands for the high flow limit alarm or the low flow limit alarm. One must parse the states if digital tests are to be conducted.

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