GE GFK-1541B manual Value Meaning

(Word 11) Number of Time Units for Read Period:

3

AChannel command set up to issue a single read can have only one pending read transfer.

(Word 7) Channel Command Number: Word 7 requests that a read channel be set up. If the command is processed successfully, it will result in attempting the specified number of transfers from the server to the client.

(Word 8) Channel Number: Word 8 specifies the channel to be used for the read. This value must be in the range of 1–32 for the Series 90-70 Ethernet Interface (Type 2) and 1–16 for the Series 90- 30 Ethernet Interfaces. If the channel number is out of range, a command error indication will be placed in the COMMREQ Status word. If the channel number is the same as a channel already in use, the channel will be retasked to perform this new command.

(Word 9) Number of Read Repetitions: Word 9 specifies the number of reads to be performed before automatically completing the communications request and closing the channel. If this value is set to 1, only a single read will be issued. If this value is set to 0, reads will be issued continuously on the requested period until the channel is aborted.

(Word 10) Time Unit for Read Period: Words 10–11 together define how often the read is to be performed (read period). Word 10 specifies the time unit such as seconds or minutes for the read period. Word 11 specifies the number of those units. The choices for the time units are shown below.

Value	Meaning
1	hundredths of seconds	(10 ms)
2	tenths of seconds	(100 ms)
3	seconds
4	minutes
5	hours

Note: If Time Unit Value is 5 (hours), then the maximum usable value of Number of Time Units is 5965.

Word 11 specifies the number of time units for the read period. The read period is in effect even when the Channel command is setup to issue a single read.

Example Read Period Calculation: If Word 10 contains a value of 3 specifying seconds as the time unit and Word 11 contains a value of 20, then the read period is 20 seconds.

A read will normally be issued at the start of each read period. If the pending read transfer has not completed during the read period, the Channel Error bit and Detailed Channel Status words will be set to indicate a non-fatal period error. The pending transfer can still complete after the period error occurs. For Channel commands set up to issue multiple reads, the next read transfer will be issued only after the pending read transfer completes.

If the Number of Time Units is zero, a subsequent transfer will be issued as soon as the previous transfer completes. In this case, no period errors can occur.

GFK-1541B Chapter 3 Programming Channel Commands 3-11