PSC Magellan 8500 Service Manual download pdf (Page 49)

METTLER TOLEDO

DIVA Service Manual 43

6.1.4 8213 Mettler Toledo

6.1.4.1 Host Communications

The 8217 scale acts as a peripheral device when connected to a host computer. When the host

requests weight data by sending an uppercase W, the scale will respond with the weight data or a

status byte if the scale is in motion or an invalid state. The host can also request a scale zero

operation, in which case the scale will respond with the scale status, so the host can determine if

the scale is in zeroing range and/or if the scale is at zero. A scale confidence test can also be

initiated by the host to cause the scale to perform RAM, ROM, and NOVRAM tests and put the

results in a status byte for later interrogation by the host.

Data is transmitted and received by the scale using an RS232 voltage level interface in the

following ASCII format: 7 bit even parity and one stop bit. Data transmission rates are 1200, 2400,

9600, or 19200 baud asynchronous. The host computer must send requests to the scale as

specified single uppercase ASCII characters to have it perform various functions. The scale will

send a response back to the host computer as a string of ASCII numeric digits or as an ASCII ?

followed by a status byte. There must be at least a 200-ms delay between commands to allow for

processing data response time at the scale. The following table shows the standard commands and

responses between the scale and host. If a confidence test results in an error, the scale will not

respond to the W or Z commands until the error condition is corrected. An error will also cause the

scale to halt any weighing operation until cleared.

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PSC Magellan 8500 Service Manual Page 49